It depends on whether the frame came from the road engineers, or the MTB engineers ... Road bikes are measured in cm, MTB's are measured in inches.
And as the MTB frames get more unisex and made for dropper seatposts, the measurements get further away from what we were used to.
Crank to seat height, seat to bar reach, bar elevation to seat all play a huge role in fit. But many frames can be accessorized to get into a good comfort zone. Stem length and angle, seatpost off-set, even crank arm length can all be tweaked to get you riding comfortably. Don't toss the odd bike just yet. Ride it for a while and see if you can dial it in
