jam box vs stereophonic system

jam box and stereophonic system both are nouns.

Word	Noun	Adjective	Verb	Adverb
jam box	Yes	No	No	No
stereophonic system	Yes	No	No	No

As nouns, stereophonic system is a hypernym of jam box; that is, stereophonic system is a word with a broader meaning than jam box:

jam box: a portable stereo
stereophonic system: reproducer in which two microphones feed two or more loudspeakers to give a three-dimensional effect to the sound

Other hypernyms of jam box include stereo, stereo system, stereophony.

jam box (noun)	stereophonic system (noun)
a portable stereo	reproducer in which two microphones feed two or more loudspeakers to give a three-dimensional effect to the sound