Just in case it wasn’t clear, the Mayflower is two separate properties in one. Most of the property is a hotel, but two (I think) or maybe three floors are MVC timeshares. After a recent renovation, the hotel rooms are much nicer than the timeshare rooms.
Booking with Abound points you will definitely get a room on one of the timeshare floors.
Booking with Bonvoy points, you need to pay close attention as it’s possible, but not likely, to get a timeshare room that way, but much more likely that you’d get a hotel room. I actually think the hotel and the timeshare are listed as different properties in Marriott's reservation system, so if you’re searching at the hotel it should only offer you hotel rooms.
As others have said, you’ll get all the Bonvoy status benefits, potentially including breakfast in the very nice restaurant, if you are staying in the hotel or probably if you’re staying with Bonvoy points. If you use Abound points you will not get breakfast or other status benefits.
You really have to look at what the cost for your stay would be in each currency to decide which is the better deal, then decide whether things like free breakfast move the needle for you or not. Some people never eat breakfast and so they could care less about that; but if you’re a breakfast eater, the hotel breakfast is probably worth at least $25 per person per day.
You probably need to be Bonvoy Platinum or higher to get free breakfast on a hotel stay if I’m remembering correctly.