No, it's not. The designation is 30 caliber. Virtually ALL 30 caliber cartridges fire a bullet that is 0.308 in diameter There are one or two exceptions but they still call them 30 cal and all are in the 30 cal section of the reloading manuals. Even the military refers to them as 30 cal. ,So it is correct to call any cartridge that has a bullet of 0.308 diameter a 30 caliber. You can pick nits and say they should have been called 308 caliber, but history says different. The three oh eight is the cartridge designation (308 Winchester) which is a shorter, less powerful version to replace the 30 ought six as the 308 can use the "short action" which is more appropriate for semi and full autos.
It also means a shorter stroke in a bolt action.