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.
Best Answer
Depending on who is speaking and to whom the statement is addressed, the phrases are generally interchangeable in that they will be generally understood by a US native English-speaking interlocutor.
That said, to the aforementioned native English-speaking interloctor's ear (i.e., mine) the term lay over (v.), & layover (n.) expresses a connotation that the pause in the journey is dictated by circumstances, e.g. an airline schedule, a travel agent's whim, or a typhoon-blizzard.
If I have a layover in Newark, I envision a night in a Motel 6 near EWR if I'm lucky, or if I'm not, fitful dozing on vinyl seats designed by Torquemada.
If I stop off in Louisville, it's intentional, not a quirk of fate. I may look forward to meeting friends for drinks at the Seelbach Hotel before heading up the street to watch the Bats play baseball.
If I stop over anywhere, it's a local call. I will be around the corner at Dave and Meghan's, for beer and bratwurst after a hard week at the word factory.
(Remember, these are idiosyncratic distinctions from my corner of the US, my generation, and my sense of language. Opinions of British cousins, travel agents, and visitors from Rumtifoo may differ.)