There are reasons to like TJ Watt over Carlton: He's more mobile, and explosive. He's less experienced at DE, having converted from TE. He's got an older brother who's one of the b best DL in the NFL, and will almost certainly help him with techniques, scouting, veteran tricks, etc.
There are also downsides with Watt: He's had multiple surgeries. He's smaller. Many of his sacks came against Tight ends or air.
There are also reasons to like Carlton over Watt: He's bigger, got much longer arms, has more developed techniques, such as posting tackles off him with his length. According to PFF, Carlton is the number one Edge rusher in the draft at getting QB pressure (sacks, hits, pressures) in 2.5 seconds or less.
IMO, Carlton has lots of upside, and I don't think it's any kind of forgone conclusion that he can't rush from RDE. While it will be harder to speed rush, most of them can't anchor as well as the RT, and are more susceptible to a bull rush.
I don't know how good Carlton's gonna turn out to be, but there's plenty of reason to be optimistic.