I really would take this time and do as much research as possible between now and June regarding the differences not only between their missions if you have to fly a desk, but also the path to get to UPT.
Posting only AF side because I have no knowledge regarding Marines. Hurricane on this site is a pilot and maybe able to answer from that side.
1. AFROTC has a make or break yr. You must be selected for Summer Field Training (SFT) to commission from AFROTC
2. AF has very few rotors, so statistically if you make it through UPT, you have a high chance of getting fixed wing
3. AF has what is called gate months, it is tied to keeping your flight pay. Basically they will say if you fly X amount of months out of Y months you will continue to receive flight pay until Z yr. Flight pay in the beginning is nominal, but the time you hit 8 yrs it is substantial, plus you are looking at bonus pay to stay longer. I can't recall, but I believe the 1st gate is 8 yrs out of 11. Saying this because basically they don't want to have you fly a desk in your early yrs. and it is most likely you will step out as an O4 to do a staff tour and typically you will come back to a flying tour after the desk. My DH's assignments throughout his career were 75% flying tours.
4. Upon commissioning out of AFROTC, you will hang at home for a while, and than most likely go casual status until your UPT class starts. They will send you to IFT (initial flight training) where you will fly a Doss for about 3 weeks, but that is it.
5. UPT selection for AF from AFROTC is iffy. It comes down to the needs of the AF. USAFA gets the 1st bite at the apple. That being said if you have a private pilot's license (PPL) your chances go up dramatically for UPT selection
6. Your intended major in AFROTC will matter also regarding selection, not only for SFT, but UPT. Tech aka STEM gets an edge compared to non-tech majors. My DS was a non-tech major, and he is a pilot, but he also had flight hrs and a strong cgpa. (3.4 in college).
7. How much time do you have to payback before you can walk away from either branch. For AF it starts not at commissioning with a pilot slot, or the day you start UPT, but the day you wing. You will be 33 or 34 when you can walk.
If you want to know what your life at UPT will be like, search for a member here named Raimius. He has a blue tag line as his signature that you can hit to read his blog. The 1st few pages are about USAFA, but than he will walk you through every phase of IFT and UPT.
I stated in the beginning of this post do it by June. The reason why is most colleges do orientation starting the end of June. You will meet with a college advisor to schedule classes. AFROTC has LLAB and PT. Let's say they have LLAB at 2 on Weds., but your Chem class goes until 2:30. You can't schedule that class bc you need to be at LLAB.
Finally, in your post it appears you know which college. Contact the AFROTC unit and ask to meet not only the CoC where you can ask pointed questions, but ask if you can meet with cadets that did get a pilot slot with a major like yours. Tech or non-tech. Give them ample time to set up the cadets to meet you. Take your folks for the 1st few minutes, so they too can ask questions, but plan them to leave and meet you somewhere else on campus an hr later. You want to have that time without them. Cadets will be very respectful to parents, whereas, you alone will be just kids talking one on one.
Hope that helps.