I apologize in advance for this but sink installation is not our forte', and we want to be sure we understand so we make the right decision.

We're going to install granite and a silgranit undermount sink. I'm seeing two versions that can be used for undermounting, one is less expensive but is designed for both top mount as well as undermount. It says it requires a 35 inch cabinet but is that the only difference? Would love to save some $$ but don't want to buy if there are other less obvious reasons why we shouldn't. Help?? Any input is appreciated!