Mere difference in connotation. I attribute my good luck to the gods, and would be annoyed at the implication that such an attribution is irrational justification obscuring my good luck's allegedly-actual origin in my optimistic outlook or whatever. By my lights some non-negligible subset of superstitions give good luck due to the combination of ones instincts, cultural inheritance, and also quite crucially the help of the gods. This is compatible with what you said but I wanted to emphasize the importance of the gods, without which I suspect many superstitions would be pointless. It's true that as you imply maybe even in the absence of gods superstitions would still be adaptive, but I'm less sure of such a counterfactual than of this world where there are in fact gods.