Front loaders are generally gentler on clothes because they only spin and don't oscilate at all. Also they don't have a spiny tube thingy in the middle.
Not OP but i just found an answer. Top loaders may have a center agitator which is there to ... agitate more -- which we don't want to do.
Any machine that is without a center agitator will be more gentle on clothes and less likely to cause shrinking due to fiber damage and consolidation. If you have a top-loading washer with a center agitator, reduce its impact on your garments by opting for a gentle or hand-wash cycle.
(from the same link that i posted in another comment)