They are often used interchangeably but there are minor differences:
Situated: (formal) = where something is / where you can find something (like building or places in nature)
Located:
A) To put something in a particular place: The school located its gate near the street.
B) If something or someone is located in a certain place they are at or in that place: The convenience store is conveniently located. The bathroom is located on the 3rd floor.
So, situated is more formal. Located is more casual. Even though there are some minor differences it's usually okay to use them interchangeably.
Lastly, some people might also argue that situated means that something is put somewhere deliberately (like an office on the 3rd floor) whereas located means that something has always been there or been there for a very long time (like a mountain).
Good question, I think many people are going to have many different answers to this question.