"Mountain" is the everyday word for this geographical feature. "Mount" is mainly restricted to place names -- it is used in the names of specific mountains. For example, "Mount Everest is the highest mountain in the world".

Mountain is a terrain feature, one climbs it. Mount can be: noun, a horse, verb, the act of getting on top of, verb, to prepare to launch or attack noun, an ornamental fixture on a book or piece of furniture

"Mountain" is the usual word. For the name of one particular mountain, there are two common patterns: "X Mountain" and "Mount X." Whatever the map says it is called, that's what you must call it. Mount Fuji in Japan is Mount Fuji, NOT Fuji Mountain. Sugarloaf Mountain in Brazil is Sugarloaf Mountain, not Mount Sugarloaf. "Mount" does have a legitimate dictionary meaning for any relatively high place--possibly no more than a hill. This use is VERY RATE and OUTDATED. An old account of a church building says "the aisle which should have been north, is on the east... Drake thinks it was in consequence of the disposition of the ground, which forms a lofty mount on the east."

Mount is the abbreviated way to say mountain, the same as bro to brother.