Final answer:
Two distinctive features to tell apart a snake from a legless lizard are that snakes do not have eyelids and lack external ear openings, whereas legless lizards have both.
Step-by-step explanation:
To distinguish a snake from a legless lizard, there are two key features that you can look for. The first feature is that snakes do not have eyelids; instead they have a clear scale that covers their eyes. In contrast, legless lizards have functioning eyelids. The second difference is the presence of external ears; snakes lack any external ear openings, while legless lizards have visible external ear holes. These features are significant because they are related to the evolutionary adaptations of snakes and lizards, with snakes evolving from lizards and adapting to their environments in different ways over time.