there are two types of projectiles typically used in Airsoft launchers,
1) moscart shells, that are effectively shotgun style shells that you load up with between 18-200rounds and shoot out all one one go be that in m203, M79 or rocket launcher. They all do the same thing.
2) an actual projectile. I typically use TAG innovation rounds, that either explode on impact or after a certain flight time or even that deploy smoke. But you can also use NERF rockets too
Check out this video from circa 7 years ago where I use an explosive 'archangel' TAG round to shoot a dude behind cover.
https://youtu.be/y47tupfDxC4
Tag rounds really do transform the grenadier class into a really useful accessory to carry, but not all sites let you use them though.