cayman diver:
the real diffrance is you can pee in a wetsuit but don't even think about that in a drysuit!!
what about a p-valve ?? could not imagine to have no p-valve on my suit 2-3 h diving in coold water 35-36 degrees, while doing the hang you have to drink as well .
no chance to survive this time , even in a very good semdry suit.max time you will do in this water will be about 45-55 min than it is over with the fun and more difficult to imagine is the second dive wich won't be longer than 20-30 min
i would deffently recomment a drysuit but the undergarment has to be a good one as well , if you dive trilam or quadlam .
a other drysuit is neopren 2mm or 3mm crashneopren .
and don't dry to safe mony on the suit get a good one , inform yourself so much as possible ,and try so much as possible .
to stay as flexible as possible it need's a good fit , by a cheap one ,i can garantie you will regret it soon .
customfit would be best .
the currently one i have is from whites they had 16 stock sizes fond the right one ,but my next one will be a customfit 2mm crashneopren from dui ,good for ice diving.
so depends on you what your diving future will be ,do you want to dive cold , do you travel as well or not than there will be the waight to be considert ,trilam is not as heavy as crushneopren . if you dive just warm water than you are better of with a regular wetneopren suit or samidry wich is wet as well but you don't have as much waterexchange because of the wrist ,neck, ankel and zipper seal wich you don't have on the wet wet suit at all, semidry and cold than you have to get 7mm +7mm or 5mm icewest .
there is a lot fine information you can find on the internet , the only thing you have to do is devot your time to research.
DUI
BARE
WHITES
just to name some of the drysuit manufac.
handerson is a very nice fitting one with hyperstrech the second skinfit very importand .
i hope i could help you , good luck with you research and your decitions you make