I usually start throwing in more isolation when cutting to harden up and define the muscles, but it's almost the same.
This has never made sense to me. I usually keep some form of isolation movement for my bis, tris, and rear delts, but I've never understood the idea that these are specifically good for what you have proposed (harden up and define the muscles). Isolation movements to me are the things that I do to blast a specific muscle/muscle group that I know will recover quickly and that won't burn out my CNS.
It's hard to blast a muscle to pieces when cutting.
So I keep my reps within 3-6, on some smaller movements to 8. I do this anyway, but I put much more emphasis on 3-6 rep range when cutting. I follow the school of thought that your body doesn't need a lot of muscle to move a lighter weight for a ton of reps, but it does need a ton of muscle (also type 1 muscle fibers which are bigger and stronger/faster) to move a heavier weight for less reps.
Diet, though, is key. People are afraid of carbs, but they shouldn't be when dieting. Beans are an amazing source of carbohydrates when dieting. I also like to keep fats and carbs separate when I can.