sub vs escape hatch

sub and escape hatch both are nouns.

Word	Noun	Adjective	Verb	Adverb
sub	Yes	No	Yes	No
escape hatch	Yes	No	No	No

sub (noun)	escape hatch (noun)
a submersible warship usually armed with torpedoes	hatchway that provides a means of escape in an emergency
a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States

sub (verb)	escape hatch (verb)
be a substitute