streak vs colour in

streak is a noun but colour in is not a noun.

Word	Noun	Adjective	Verb	Adverb
streak	Yes	No	Yes	No
colour in	No	No	Yes	No

As verbs, colour in is a hypernym of streak; that is, colour in is a word with a broader meaning than streak:

streak: mark with spots or blotches of different color or shades of color as if stained
colour in: add color to

Other hypernyms of streak include color, color in, colorise, colorize, colour, colourise, colourize.

streak (noun)	colour in (noun)
a narrow marking of a different color or texture from the background
a distinctive characteristic
a sudden flash (as of lightning)
an unbroken series of events

streak (verb)	colour in (verb)
mark with spots or blotches of different color or shades of color as if stained	add color to
move quickly in a straight line
run naked in a public place