There is one difference, which is that popping a nuke over a live target would make a Very Big Statement: "You have crossed a line that we believe now makes you an existential threat. Consider your next move very carefully." Which would then prompt the adversary, staring into the abyss, to search their soul a little before pressing matters any further.

(Or so goes the theory, anyway. In reality nobody knows how a nuclear-armed adversary would respond to that Very Big Message, because it's outside the realm of previous human experience. For all we know it could have the opposite effect, causing them to panic and unload their whole nuclear arsenal out of fear.)

DU is not a "nuke". It's kind of the opposite. It's the byproduct of the process of separating the more active isotopes from the almost non-radioactive one, U-238.

you do not need to hit the target directly. plus those rocket launchers are not in bunkers.