like (adj.) is used to make a comparison example: He looks like me. example: She acts like the president. example: Like Bob, Susan wears red socks.
Like should be followed only by a noun or a noun phrase. It is never used as a conjunction.
As or as if (conjunctions) should be used if your comparison involves action example: His sports car is faster than his station wagon, as it should be. example: Ralph ran as if his life depended on it.
In both cases, the “as” or “as if” is a conjunction that joins the two clauses.
Such as means for example. example: For breakfast he cooked local specialties such as grits and red-eye gravy.