Even for cues that have the same line names for both pool and carom, there are differences in taper, as well as weight and therefore balance between pool cue butts and carom cue butts.
In general Carom cue butts have a straight taper, with an overall slightly lighter butt weight on average.
Carom cues also have a lighter joint (Titanium Uni-Loc Quick-Release for carom cues made from 2020 or Aluminum Radial for the original Predator carom cues from 2011-2013). In comparison, pool cues usually feature a stainless steel Uni-Loc joint that is slightly heavier.
Diameter at the Joint:
The diameter at the joint is the same, which means that carom and pool butts and shafts are interchangeable.
The length of carom and pool butts is also the same (29").
Carom shafts are however shorter than pool shafts (27.25" for carom shafts Vs. 29" for pool shafts).