Hi Darrell, The smaller boat is a simpler kit in 1/125 scale that my mother gave me. Bless her heart, I can't believe she even remembered me talking about it. Aren't Mom's great! The hull is cut open with a very simple interior. With some work it can be made into a nice model. It's really more of a kids kit. The larger Revell 1/72 kit is killer. There are SO many after market items available for this kit you just can't believe it. Yes, you can cut the hull open and add several available compartments if you wish. But with this kit, you will have to open the hull up yourself. Since this is my first boat, I will probably just concentrate on the hull details and see how I do with that. I've wanted this kit for a while now, and now they have a US Gato Class sub coming out in 1/72!!! Does anyone know what the differences are between this boat and the "Atlantic" version boat Revell is releasing??