They are both .32 or 8mm rounds. Just as 7.62x51 and 7.62x54r are both .30 caliber. What sometimes gets lost is how the "round" was measured. Was it the old style lands, or the new fangles grooves?
7.92 which is what would be on Military ammo is actually .3118", so the original designation was lands, New 8x57 uses a .323 bullet, that is 8.20mm. 7.5 is .308, 7.62 is .311. Can I confuse you more??