Not at all. One is traditional and the other modern.
It's just my opinion, but I feel a sidelock should use traditional ammo which is a PRB to me. I wouldn't use anything else. Actually, it's all i've ever used for muzzleloader hunting.
Inlines are modern and should use modern ammo. I made the mistake of using real BP in an inline and old style lead conicals. Along with open sights thinking I was at least keeping part of it traditional. That's dumb thinking and i'm fixing it now. I'll use a scope, modern bullets and BH 209 in the inline.
My opinion only, but it's a strong one.
Putting a fast twist barrel on a sidelock and shooting sabots is ridiculous.