the most obvious difference is in the feelers, or antennae. most butterflies have thin slender filamentous antennae which are club shaped at the end. moths, on the other hand, often have comb-like or feathery antennae, or filamentous and unclubbed. this distinction is the basis for the earliest taxonomic divisions in the lepidoptera the rhopalocera ("clubbed horn", the butterflies) and the heterocera ("varied horn", the moths).