If you like to compare apples and oranges, here is a more detailed one:
Similarities:
- both Sleep and Hold Person/Monster are spells
Differences:
- without upcasting Sleep is designed to get rid of several small threats (avg. 3-4 goblins, 4-5 kobolds/stirges from MM) or one medium, Hold stops a single big threat (no HP limit)
- Sleep doesn't have saves, but is countered by slap (action) from an ally, Hold saves on WIS
- Sleep ends on hit, first hit is with adv. and autocrit from 5ft, Hold doesn't end on hit, so the whole party attacking paralyzed enemy (adv. + autocrit) effectively make caster holding concentration deal something like 50% of the entire party damage (all melee fighters damage that wouldn't hit without adv. and wouldn't crit is attributed to caster)
- Sleep is ineffective when enemies are spread or already in melee (can sleep your allies at low levels), Hold is targeted, upcasted can handle multiple threats coming from multiple directions
I believe we all agree concentration doesn't work well in BG3 and here are some reasons for that:
- Larian's homebrew prone breaks it (D&D prone doesn't)
- Larian's homebrew autohits from Fire Bolt cause multiple concentration saves
- Larian's homebrew acid surface break concentration
- lack of basic protection tool, i.e. Shield spell
- lack of relevant feats
- lack of Sorcerer (CON save prof) or multiclassing (e.g. Fighter 1 / Wizard X)
- silly AI (no DM would go after your casters in every battle)
