I experienced the opposite journey just this last week. I was in coach, all that was offered were tiny bottles of water, given out to each passenger. No passengers received any food aboard the bus, but whether we were all "coach" passengers or mixed, I couldn't say.
We called at each station en route from Albany to Boston, picking up additional passengers and discharging original passengers accordingly.
Coach was pretty full, only the Amtrak staff were able to reserve two seats each to themselves. Bus toilet facilities were good, a modern vehicle.
We passed through some interesting towns along the way, seeing more scenic views than one would get from the train.
My advice, if you feel you will need to eat between Boston and Albany, pack some food!