A comparison in which the words as or like are used is the

It is a simile. A simile is comparing two things with like or as. Example: "They were as quiet as a mouse". Now never confuse this with a metaphor which doesn't use like or as, but still compares two things. Example: "She is a walking encyclopedia". This is telling you indirectly that she is a very smart and talkative person. A simile would tell you directly