Much will be determined by where they get accepted.
At USUHS, they are on active duty with full pay, allowances (including the tax-free BAH housing allowance) and have all the benefits such as TRICARE. They start out right away “student doctoring” at Walter Reed NMMC.
At a civilian medical school, I believe tuition, books, student health plan and a living stipend are provided, and they are in inactive Reserve status.
Of the sponsor mids in our family who have gone the med school route, it’s been about a 50/50 split. There have been those who have gotten into a top tier med school and knew that was the diploma they wanted hanging on their wall. One sponsor son got into several fine schools, but elected to go to USUHS for the financial stability and benefits. Of course, USUHS is also a fine school. He married his fiancée right after USNA (2% club, had been together since they were Senate pages) and knew they wanted to start their family in medical school. The student health plan did not include family (I don’t know if that has changed), but as an AD officer, he and his family had full free TRICARE coverage.
The USNA coaching group for these selectees has a pretty good idea of where their MCATs, USNA degree and GPA will get them in.