Man of the F, 7.62 x 51, or 7.62 Nato, is the military designation. Sporting arms, which in Canada as a newbie are the only kind you will be able to purchase are designated .308 Winchester. The cartridges, while not identical, are almost universally accepted as interchangable. But in the gun store, if you ask for a 7.62 (whatever) you will get either a 7.62 x 39, the Communist medium caliber of AK/SKS fame, or perhaps some guy will try to sneak a 7.62 x 54 by you. If you ask for a .308, or more properly, a .308 Winchester, you will get a modern firearm in a versatile cartridge, available in bolt, semi, pump and lever guns, capable of dispatching all of North America's big game.
Many will dispute that last claim, and certainly purpose bought, single species rifles are a common symptom amongst those of us afflicted with gun lunacy, but we have to keep telling ourselves that we really NEED that .416, or .404, or .458, or .30-378 for gophers. Otherwise, we have no reason to haunt the candy shops.