Hi Kate,
As Bob mentioned above, this machine has the orbital transmission which results in a shorter, faster agitation stroke than your current machine. Experts here have said it's an improvement over the older type of transmission Maytag used until mid-1987 -- if you can even imagine a Maytag automatic washer that's supposedly more dependable than what earned Maytag its stellar reputation in the first place.
The tub size can be determined by checking the agitator. Standard tub agitators have three holes down the side and larger ones have four holes. The "load sensor" agitators have no holes, but I think by the time they were introduced, Maytag was only producing large tub machines.