Interesting point. At what point is it a compact tractor and not a garden tractor anymore?
Personally I would say if it's backhoe capable , that's a good indicator that your no longer in Garden Tractor territory. That's not a hard and fast rule however. Neither is this one, if it comes with a mower deck (included in the price of the machine, not as a separate attachment) then it's a garden tractor.
These days the riding lawn equipment category (and a little beyond
) is broken down like this:
Rear-engine Riders (picture the Snapper riders that were popular in the 70's/80's)
Lawn Tractors, Front engined machines with mid mounted mower decks - NOT rated for ground engaging attachments like a tiller.
Garden Tractors - Also front engined machines (generally, Gravely just had to be different,
) that ARE designed to run tillers and other ground engaging attachements.
Sub-Compact Utility Tractors - SCUT (Think Kubota BX, John Deere 2210, 2305, 102x machines) Generally loader/backhoe capable machines that also have mid-mount mowers available. Rear PTO and 3 pt hitch is present as well.
Compact Utility Tractors - Rear PTO/3 pt hitch, Definitely loader/backhoe capable, generally 20-60 HP. May or may not have a mid-mower option. Within this category there are three frame sizes, small (Deere 2x20 series or Kubota B3030 type machines), medium (Deere 770/790, 3x20 series), and large. (Deere (4x20's, 970/990, etc.)
Utility Tractors - Basically small farm tractors that may not have fully adjustable tread width, dual tire options, etc. Examples are the Deere 5000 series machines and the Kubota M series.