I'll list a few of the differences between a snake and a legless lizard
1. Snakes lack eyelids and instead use a clear scale (brille) over their eyes, while lizards (except for some species of geckos) have eyelids
2. Snakes don't have ears and pretty much "hear by feeling vibrations against their epidermis, while most lizards possess visual earholes (earless lizards have internal ears).
3. Scales = snakes have certain scale alignments and patterns (scale rows) that differentiate from snakes
4. Organ systems = snakes have very unique organ systems like "tracheal lungs" and sometimes even a "vestigial right or left lung".
5. Prey = snakes that obtain lengths of over 1.5 feet generally will eat rodent babies, eggs, inverts, salamanders, fish, other snakes, and frogs...........the legless lizard though, tends to stick with just inverts
teeth = snakes have fangs........the typical harmless snake belongs to the family Colubridae and is distinguished as "Rear-fanged". Legless lizards however don't have fangs....they have actual very tiny serrated teeth.
Tail vertebra = snakes vertebrae bones are fully calcified and attached with complete catiligaments, while lizards tend to have "break points" in their tail vertebrae that are capable of separtating from the rest of the body and closing of the circulatory veins/ateries at the point of breakage.
Limbs = legless lizards still posses actual bones from feet inside their body, while (most)snakes just possess remnants of a pelvic girdle.