Yes, leaf worms are earthworms. There may be a number of different kinds of earthworms that get labeled as "leaf worms" - common names like that are used however a seller wants to use them. If the worms are small, very reddish, and banded in color, it's possible that they are compost worms, which some axolotls refuse to eat. But there's no harm in trying them.
If your bait shop also sells Canadian nightcrawlers, these are great, I've rarely seen any sal refuse to eat them. They must taste like candy! But they are large and may require chopping.