>>96847159
Levels are less important in older D&D systems.
It's a lot more reliant on your equipment and your skill as a player than it is anything on your sheet.
< Here's OSE, which is just B/X D&D.

If you were to bring a Level 1 Fighter into a party with a Level 5 Fighter already in it -as well as other classes of disparate Levels because XP wasn't unified, they all leveled at different rates- then he'd only have
>between 4-44 less HP, adjusting for CON Modifier of -3 to +3/Level
>10% worse THAC0, 19 vs 17
>10% worse Saves, each one worse by 2 on a d20

That's it. I know 44 is a lot of HP but that's rolling max every level and having 18 CON which is VERY unlikely. It'd probably be more around 20ish HP difference.
There's no abilities they haven't unlocked yet. No archetypes or super powers.
It's only through the lens of modern D&Dogshit that a discrepancy in Levels seems like doom.