There is very little difference between the words "prayer" and "worship". But they do not mean exactly the same thing.
The basic difference in this day and age, is that worship is only directed to God but prayer can be directed to either God or the Saints.
So, what is prayer?
Let us begin by studying about the word, "prayer", what it means today and what it used to mean long ago.
To pray is to communicate with God or the Saints, our faith, our love, and our wants. So, we can say that prayer is communication.
Prayer today is basically considered an act of faith in God. An act of worship. A Catholic and Protestant can agree upon this. But, for some strange reason, Protestants tend to give a word one meaning and deny the fact that most words have multiple meanings. Therefore they deny the fact that prayer has another very important definition, and it is still seen in books which are written in the ancient language. One of those is the King James Bible:
And they all with one consent began to make excuse. The first said unto him, I have bought a piece of ground, and I must needs go and see it: I pray thee have me excused.
Notice that in this verse, the word "pray" is used in the sense of petition, beseeching or begging. And this is the other sense which the Church recognizes in the word, "prayer".
Therefore, today, there are at least three religious senses to the word "pray".
1. We can pray to God in the sense of praise, worship or adoration.
2. We can pray to God in the sense of petition or request.
3. This one requires a bit of further explanation. As we have seen, a prayer or request can be addressed to anyone, God or man. In the Old Testament, prayer was addressed to God and man. But prayer was not addressed to the dead, faithful or not.
However, there is a New Dispensation in the New Testament. Jesus has shown us that those who die in the state of grace are counted amongst the living:
And whosoever liveth and believeth in me shall never die….
To prove this, Jesus spoke to Moses and Elijah on the top of the mountain:
King James Version (KJV)
1 And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart, 2 And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light. 3 And, behold, there appeared unto them Moses and Elias talking with him.
4 Then answered Peter, and said unto Jesus, Lord, it is good for us to be here: if thou wilt, let us make here three tabernacles; one for thee, and one for Moses, and one for Elias.
And Scripture tells us that all the Baptized are now on top of that mountain with the Saints:
King James Version (KJV)
21 And so terrible was the sight, that Moses said, I exceedingly fear and quake:) 22 But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, 23 To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, 24 And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.
And so, in the New Testament era, we can make prayers of praise and petition to the Saints who went before us to the heavenly Kingdom.
We do not worship them, but we do acknowledge the love of God towards them as we do towards all our fellow men.
So what is worship?
In our explanation of the word "prayer", we used the word "worship" a couple of times already. Like prayer, worship has a meaning which is universally accepted and another which is no longer used frequently, an archaic sense.
To worship is to acknowledge and praise God's authority and power over us. In today's world, worship is only directed to God.
However, worship was not always exclusively directed to God. We can see this in the ancient text of the King James Bible where Joshua worships the angel:
And he said, Nay; but as captain of the host of the Lord am I now come. And Joshua fell on his face to the earth, and did worship, and said unto him, What saith my Lord unto his servant?
However, Joshua was merely showing reverence for an authoritative figure. In older times, in America and Britain, Kings and Judges were referred to as "your worship". Because of the recognition of their authority and power.
The online dictionary says:
archaic honor given to someone in recognition of their merit.
[as title] (His/Your Worship) chiefly British used in addressing or referring to an important or high-ranking person, especially a magistrate or mayor:
we were soon joined by His Worship the Mayor
Today, we no longer use the word, worship, to describe the honor we give anyone but God. Instead we use the words reverence, honor and veneration.
I'm sure you've noticed that prayer and worship have much in common. They are almost synonymous when it comes to prayer directed to God. Prayer directed to God is the worship of God. Because any prayer directed to God acknowledges and praises His power and authority over our lives.
Indirectly, prayer directed to the Saints is the worship of God because in doing so, we also acknowledge the great thing which God has done through that Saint. Much like when we praise a painting. When we praise a painting we indirectly praise the painter who made the painting. When we praise a Saint and acknowledge the holiness of the Saint, we indirectly acknowledge the God who made the Saint.
Liturgy is the work of man. It is frequently called the Mass. It is the public gathering of the people of God to acknowledge God's authority and power over our lives. Therefore, worship is the main purpose of the Liturgy. However, the Liturgy includes every form of prayer we can offer to God. Praise, glory, honor, thanksgiving, petition, sacrifice, etc. It also includes rites and rituals which were commanded by God that we should do in remembrance of His Son.
Many people think that private prayer and worship are all that is necessary and that Liturgy is optional. But that is far wrong. It is clearly explained in Scripture that God takes great offense with those who do not honor Him in the Liturgy on the appointed day:
King James Version (KJV)
25 Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching.
26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
28 He that despised Moses' law died without mercy under two or three witnesses:
29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
30 For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people.
31 It is a fearful thing to fall into the hands of the living God.
What is the heavenly Liturgy? Scripture reveals that the saints and angels in heaven are always praying to God. Therefore, we are taught that all our prayers on earth are linked to the prayers of the angels in heaven.
This is especially true in the Mass. Where we believe that we, humans on earth, join the whole cohort of heaven in proclaiming God's glory. This is why the Church recommends that we pray continually in order that we may always be united to the Mass and to the heavenly Liturgy of the saints and angels.
With that in mind, through the centuries the Church has given us many tools in order to encourage us to pray continually.
The Liturgy of the hours
The Divine Mercy chaplet
and many, many other devotions are taught by and supported by the Church. We should take advantage of these and to the yearnings in our heart in order to always remain united to God, wherever we may be.
I hope this helps. Let me know if there is anything which needs clarifying. See also New Dispensation and Prayer for the dead.