Both powders are manufactured by ADI of Australia.
H-4895 is slightly faster burning. This means you use less of it than Varget in a given load, all things considered. By the same token, it reaches maximum pressure sooner. It is better for slightly lighter bullets in the .308.
Varget is a universally excellent powder for the .308 with bullets of 150 grains or heavier. It's probably the most commonly used powder these days in .308 target rifles.
Given that you plan to load for the Russian cartridge as well as the .308, I'd personally choose Varget out of those two powders.