jamming vs ECM

jamming and ECM both are nouns.

Word	Noun	Adjective	Verb	Adverb
jamming	Yes	No	No	No
ECM	Yes	No	No	No

As nouns, ECM is a hypernym of jamming; that is, ECM is a word with a broader meaning than jamming:

jamming: deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
ECM: electronic warfare undertaken to prevent or reduce an enemy's effective use of the electromagnetic spectrum

Other hypernyms of jamming include electronic countermeasures.

jamming (noun)	ECM (noun)
deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems	electronic warfare undertaken to prevent or reduce an enemy's effective use of the electromagnetic spectrum