AIR at the end (example: Korean Air)
Means coach class will be uncomfortable.
AIR at the beginning (example: Air France)
Means coach class will be unpleasant.
AIRLINES (example: United Airlines)
Means coach class will not be comfortable.
AIR LINES (example: Delta Air Lines)
Means coach class will not be pleasant.
AIRWAYS (example: British Airways)
Means coach class will be a drag.