Several billion dollar target groups of the most advanced technology in the world. Still vulnerable to that rogue missile, swarm or targetable ICBM carrier killer that comes from straight up.
They are a projection of power against an enemy without the means to respond. One good nuke makes them flotsam.
"One good nuke" against any target would result in the same, relevant difference is a CVBG can move, do so quickly and thanks to various stealth tech, can be relatively invisible while doing so.
Carriers are mobile air bases that allow us to project power globally.