That's a choice among rifles not between cartridges.

The 8mm doesn't fit in a light little Kimber 84m or Remington 600, but you'll never find the .308 in a classic beauty like this:

https://www.24hourcampfire.com/ubbth.../1/Commercial_Mauser_Info_Wanted_#UNREAD

The rounds are too close to quibble about.