The difference between the two is the case. The one thing in common is that they both use a 30 cal. bullet. The 300 sav,300 mag,300Wby mag,308,30-06,30-30,and many more are all 30 cal bullets with different brass cases and designs. There is no know per say nomenclature for naming cartridges,that are USA made. Europeons do have some nomenclature in there millilmeter listings. hoope i helped vangunsmith