Originally Posted by
username
I don't think the word "layover" has specific meanings but the word "stopover" has very specific meaning in the airline ticketing/fare rule world.
I had thought, from many years ago, that layover were stops that were overnight and required a hotel as part of the booking. The etymology being that you were going to lay down during the stop. Stopovers were ones that did not necessarily require a hotel.
These terms seem to have been diluted by conflation in recent years, just as direct and non-stop have been.