Re: Ammo Cross refference
The same? Practically, yes, technically no with operating pressures being different. One example being 7.62x51mm NATO brass tends to be thicker than .308 Win. brass reducing interior space. Do a search, it's a topic that gets covered then and again.
The same can be applied to the 5.56x45mm NATO vs. .223 Rem.
Others that go by more than one would include:
.30 Army / .30-40 Krag / Caliber .30 (1892)
.30-06 Springfield / .30 Gov. / 7.62x63mm Caliber .30 M06
7mm Mauser / 7x57mm
8mm Mauser / 7.92mm Mauser / 8x57mm
280 Rem. / 7mm Express Rem.
250 Savage / 250-3000
The list can go on and on and on....