colour television vs colour TV

colour television and colour TV both are nouns.

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

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

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

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

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