Headstamps matter
Headstamps matter because they identify the maker, and sometimes year of manufacture. Different makers use different composition brass. Federal and I believe Remington use a softer brass. LC (Lake City Army Ammunition Plant) indicates quality brass was used, to make U.S. military spec ammo. In 7.62 it tends to be heavier and have reduced capacity compared to Winchester 308 brass. LC usually has crimped in primers, which must be removed to reload. THe plus side of this is that if you remove the primer crimp, you are certain you have once only fired brass and not range brass of unknown history.
For general use, getting started, and plinking away any brass will work. BUT, different headstamps should NOT BE MIXED for 308 and 7.62. The same load in different headstamp brass can have significant differences and potentially result in unsafe loads. Just do not fool around with maximum loads.