Where do you draw the line between composition and arrangement/ orchestration?

That’s a big doubt I have. I usually start my score with a piano sketch ( lets say bass and chords left hand - melody right hand for the sake of simplicity ).
i then make it into a form ( like ABA,etc.) but I don’t understand if all the things coming after that are part of the composition or the arrangement process.

What I mean by that is if having a form , chords and melody is enough to call it a composition.
Deciding how I want to “ express” the harmony, adding counter melodies, adding runs and textures, etc. is considered the arrangement/orchestration process? ( btw I see some people making a distinction between those 2 terms. is orchestration just arranging for orchestra or is it something slightly different? )

Adding accents , ostinatos, different chord Voicings are all part of arrangement?

i.e. a woodwinds runs, I think it s very much part of orchestration. I wouldn’t call it part of composition, even though I can save some notes about that in my sketch for the later orchestration process.

deciding if I want more of a block chords or an arpeggios or something else to “express” the harmony I made in my sketch is still part of arrangement?

I also struggle in finding books about orchestration / arrangement that focus more on this aspect. They tend to spend most of the time talking about the technique of playing and sound of the orchestra members.

do you think reading some scores is the way to go to learn how to turn a simple piano sketch into an arrangenent?

should I add more aspects to my composition process ( like writing countermelodies, bass lines,etc. already in the composition phase) or are they more of an arrangement topic?

thanks for helping me