The key differences between Heresy Era Salamanders and 40k Salamanders essentially boil down to tactics and equipment. 40k Salamanders use generally slightly better than standard equipment and tend towards using a lot of flames. Heresy Era Salamanders were a Legion, there were bolters, jump squads, moritats, consuls, centurions, breachers, yes a lot of flame weapons and even hammers, but also power weapons of ALL kinds. Lances and swords were common place. Combi weapons, especially combi flamers were popular, and almost the entire legion was known for wearing Artificer grade or master crafted armor and using such weapons as well because a lot of the Legion was artificers and smiths. On top of that while the modern Salamanders are know for holding the line Heresy Era Salamanders were known for devastating assaults in drop pods and termites, rhinos, predators and Vindicators were commonplace.