That's what "similar" means. It means almost the same, but not exactly.
Here are some examples:
* My sister and I are similar because we both have brown hair and love to read. (We share some qualities, but we aren't exactly the same)
* This shirt is similar to the one I have at home. (They look very alike but aren't identical)
* The weather today is similar to yesterday. (It's not exactly the same, but close enough to notice)
To help you remember, think of the word "similar" like "same but a little different."