Different outcomes. Moab is fuel air explosion and causes massive pressure wave disruption, it's usable against tunnels but operates on a different principle. Bunker buster is an earth penetration weapon to make a camouflet happen and destroy structural integrity.

Today's word of the day for me

https://en.wikipedia.org/wiki/Camouflet

> A camouflet, in military science, is an artificial cavern created by an explosion; if the resulting structure is open to the surface it is called a crater.[1]