Here’s my take:
Worship stems from a response. Christians, who might as well be the target audience of this question, respond to God. They respond to a relational experience they have with God. Any song that thus serves to bring about the aspect of this relationship between man and God and man’s response to God, serves as worship music.
If I may go a little further, this response is to God’s provision of both Himself and His benefits
For example: Songs that exalt God for who He is, that praise Him because of the beauty we see in creation, that lift His Name in reverence of what He can do etc are worship songs
On to Praise Music
We humans… Christians… mankind… whatever you wanna call it, have made this distinction between praise music and worship music.
If anything, there just might not be much of a fence between the two.
But this I’ll bring to your attention:
Praise is part of Worship.
And not the other way around.
We defined worship as a response to our relationship with God. Well, I can choose to/be led to response to God via praise, or via being diligent in my work. Both are worship, but not both are praise.
What then is praise?
I’ll define praise as this:
Musical, hearty worship
Songs of gladness, songs we sing to praise God for His good deeds, songs that lift His Name for who He is etc
You can start seeing that already, there is an overlap.
But that is to be expected, as praise is indeed part of worship. Worship is but an umbrella term, and praise its secondary…one of many expressions of this response to God.
So, does that mean…
Hymns are another means of worship music.
Hymns are a bit specific though
Whilst praise may infer a sense of generalisation when it comes to defining what exactly it is, though not lacking in specific identification, hymns are pretty much defined.
They are songs, written to syllabic rhyme, employing musical features such as cadence with a – mostly – definite lyricism style used through out.
Pertaining to its use, a hymn is formally sung in and by the Christian congregation. Unlike praise music, hymnal music is set to be sung by all, rather than to be led by a soloist/worship leader. As such, the form is usually an alternation of verse and chorus and rarely – if ever – a refrain or bridge. No solo parts for sure.
We could go on and on to define others such as Psalms, but I hope with this attempt at debunking the puzzlement and ambiguity between these 3, you’re better poised to delve into a richer context of understanding the music you are butted with at least on a weekly basis.
Also, feel free to explore more resources on the same. This isn’t the Shangri-la of musical answer perfection. I’m sure more accurate and informed “information” awaits your discovery.
All the best
A music enthusiast