You need to decide if you want to be a part time Marine or a full time Marine.
The USMC reserves SHOULD NOT be used as a place to serve a year or so to see if you like it before you go active. If you want active, then choose that. If you want reserves, then choose that.
If you are in the reserves and get activated, then oh well. Your life(college) gets put on hold and you go honor your obligations. Many times a 4 year degree can take 5-6 years to accomplish while in the reserves. It all depends on whether you get activated or not.
Many people today try to go reserves with the master plan of going active later on. This does not always work out in the USMC. When you choose to do this route, you cancel your contract and you are allowing the USMC to use you as they wish, if they wanted to, so remember that.
Bottom line is this. Don't enlist into either of them until you are 100 percent positive this is what you want to be in.