color TV vs colour television system

color TV and colour television system both are nouns.

Word	Noun	Adjective	Verb	Adverb
color TV	Yes	No	No	No
colour television system	Yes	No	No	No

As nouns, color TV and colour television system are synonyms defined as:

color TV and colour television system: a television that transmits images in color

Other synonyms of color TV include color television, color television system, colour television, colour TV.

color TV (noun)	colour television system (noun)
a television that transmits images in color	a television that transmits images in color