Barrel length and/or chamberings are not determining factors, actually, they're mutually exclusive. Here's what I posted in another thread on the same subject.
It's the configuration that determines whether or not it's a rifle or carbine, not the cartridge it chambers. With leverguns, our most popular pistol cartridge long guns, there are certain features that differentiate rifles from carbines. Rifles tend to have crescent or shotgun-style buttplates. Carbines have their own style of buttplate. Rifles tend to have long forends with a forend cap. Carbines have forend bands. Rifles tend to have a longer (20" plus) octagon, half octagon or round barrel with a dovetailed magazine band. Carbines have shorter barrels, usually under 20" and are always round with a full barrel band to secure the magazine tube. Rifles can have either a straight, pistol grip or half pistol grip stock. Carbines are always straight.
Take two 20" Winchester 94's. Both chambered in .30WCF. One was made in 1901, has a crescent buttplate, straight grip buttstock, a 20" octagon barrel, a long forend with cap. That is a short-rifle. The other has a 20" round barrel, a shorter forend with forend band, a straight-grip buttstock and a carbine buttplate. That is a carbine. Same model, same chambering, same barrel length, same overall length, two different configurations. One is a rifle, the other a carbine. The chambering is immaterial. Make sense?