favourite vs preferred

favourite is a noun but preferred is not a noun.

Word	Noun	Adjective	Verb	Adverb
favourite	Yes	Yes	Yes	No
preferred	No	Yes	No	No

As adjectives, favourite and preferred are synonyms defined as:

favourite and preferred: preferred above all others and treated with partiality

Other synonyms of favourite include best-loved, favored, favorite, favoured, pet, preferent.

favourite (noun)	preferred (noun)
something regarded with special favor or liking
a special loved one
a competitor thought likely to win

favourite (adjective)	preferred (adjective)
preferred above all others and treated with partiality	more desirable than another
appealing to the general public	preferred above all others and treated with partiality

favourite (verb)	preferred (verb)
To mark an item as a personal favorite on social media