Like and as are both be used to say that things are similar. Like is a preposition, and is followed by a noun or a pronoun.
We often use like after verbs of the senses (look, sound, feel, taste and smell).
As is a conjunction, and is followed by a subject + verb or by a prepositional phrase.
In informal speech, like is often used as a conjunction.
(Not) as + adjective
/ adverb + as
We use (not) as + adjective / adverb + as to say that two things are equal.
(Not) as much /
many + noun + as
We use (not) as much / many + noun + as to say that two quantities are equal. We use as much with countable nouns and as many with uncountable nouns.
Similar to, identical
to, the same as
We use similar to express the notion of similarity. We use identical to and the same as to say that there is no difference between two things.
For information about other comparative forms, see Functions and notions,
Comparison.