What is the different between compare with and compare to ?

I am confused with them.

Can someone give me an answer ?

compare A with B

A和B比较(比如：老鼠A和大象B之间比较)

－－－－－－－－－－－－

compare A to B

把A比作B （比如：把老鼠A比作大象B）

"compare with " --- when it refers to the act of examining two like things in order to discern their similarities or differences:
当涉及考察两个相象的事物以辨别他们的相似或差别时，它取with ：

The police compared the forged signature with the original.
警察将伪造的签名与原来的作比较。

"compare to" -- when it refers to the activity of describing the resemblances between unlike things:
当它涉及描述不同事物相似性的活动时，Compare 常用介词 to ：
He compared her to a summer day.
他将她比为夏天。