What's the difference between those terms? Can they be used just about interchangeably?
stopover n./stop over v.
noun A brief stop in the course of a journey, as to eat, sleep, or visit friends.
verb To make a stopover
layover n./lay over v.
noun A brief stay in the course of a journey
verb To pause some place during one's journey
Please, compare:
There's a stop-off to change planes in Chicago.
There's a stopover to change planes in Chicago.
There's a layover to change planes in Chicago.
-and-
On our way to New York, we stopped over in Philadelphia for the night.
On our way to New York, we stopped off in Philadelphia for the night.
On our way to New York, we laid over in Philadelphia for the night.
-and-
Marj decided to stop over in Pittsburg to see an old friend.
Marj decided to stop off in Pittsburg to see an old friend.
Marj decided to lay over in Pittsburg to see an old friend.