Some fussy grammarians think that there is a rule that says you should use as when comparing phrases. He looks prosperous and well-groomed, as a true gentleman always should. You should use like when comparing single words. That perfume smells like roses.
There is, however, no such rule. English speakers use like for both types of comparisons, and rarely use as.
I am not a professional teacher. The two words 'As' and 'Like' can be used as Adverb/conjuction/ pronoun/preposition while the word 'Like' can be also used as verb and noun. So depending upon the usage the meaning changes. To understand both the words, one must practice the varous uses. Here examples of 'Like' being used as adjective is given: The girl is like her mother. (Adj)
I have my likes and dislikes. (noun)