jam vs congest

jam is a noun but congest is not a noun.

Word	Noun	Adjective	Verb	Adverb
jam	Yes	No	Yes	No
congest	No	No	Yes	No

As verbs, congest is a hyponym of jam; that is, congest is a word with a more specific, narrower meaning than jam:

jam (noun)	congest (noun)
deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
preserve of crushed fruit
a dense crowd of people
informal terms for a difficult situation

jam (verb)	congest (verb)
interfere with or prevent the reception of signals	become or cause to become obstructed
crowd or pack to capacity
get stuck and immobilized
block passage through
crush or bruise
press tightly together or cram
push down forcibly