They are definitely synonyms and can be used interchangeably in many situations. However, in practice they are usually used in the following contexts. track - Could be markings left unintentionally by someone that can be followed. In use you might say "The police officers are following the tracks left by the escaped prisoner." However, it can also be used as a pathway built for a race. Such as a race track. The track could be used for cars or people running on it. trail - Is mostly used in the context of nature. A trail in the woods. Or could be used to say something along the lines of following someone. "I am trailing someone." "They are hot on his trail" Very similar words, it will just take experience to know which one is typically used in each situation. Here is a fun sentence for you. "As the runners round the the final turn on the track, Ben is right on Matts trail."

A track is a path made by repeated passage of people, animals or vehicles, rather than by design. Tracks (plural) instead are the marks on the ground and vegetation left by the passage of an animal, a person or a vehicle (tyre marks on the ground, broken twigs, footprints, shifted grass, etc.)that can be followed in pursue. A trail is a sign left by the passage of something as well, but it's more general: it's not limited to marks, it can be something dropped or left behind such as blood, smoke, smell, scent, water, motoroil, etc. It's also meant to be a continuous path that leads you to the agent that created it without interruption. Of course, this is a general explanation, there are collocations and personal preferences of each speaker that are important.

Are you asking about nouns or verbs?