jet bridge vs overcrossing

jet bridge and overcrossing both are nouns.

Word	Noun	Adjective	Verb	Adverb
jet bridge	Yes	No	No	No
overcrossing	Yes	No	No	No

As nouns, overcrossing is a hypernym of jet bridge; that is, overcrossing is a word with a broader meaning than jet bridge:

jet bridge: an extendible bridge for loading passengers onto large commercial airplanes; provides protected access to the plane from the gate
overcrossing: a bridge designed for pedestrians

Other hypernyms of jet bridge include footbridge, pedestrian bridge.

jet bridge (noun)	overcrossing (noun)
an extendible bridge for loading passengers onto large commercial airplanes; provides protected access to the plane from the gate	a bridge designed for pedestrians