The 7.62mm M80 Ball round is for use against personnel and unarmored targets. It has an unpainted bullet tip and is known by three other names: 7.62 x 51 mm, 7.62 NATO and .308 Winchester.
If asked about the 7.62x39mm cartridge (aka the 7.62 Soviet and .30 Russian Short), the first firearm that comes to mind is ...