The 1-A is the light sporter
1-B is the standard
1-H is the tropical which is the sporter in very large calibers often used in African Safaris.
1-K1-BBZ is the stainless with laminate stock. (the above versions are all available in this model too)
1-RSI is the International full manlicher stocked.
1-S is the medium sporter (slightly heavier barrel, like 1-H)
1-V is the Varmint which has a heavy barrel and no rib.
The #3 is a carbine, which has the forearm held on by a band, and a S style lever, rather than traditional #1 lever setup., and carbine buttplate.
Hope this helps.