'Identical' means something is an exactly replica of something. For example, you can have identical twins (they look exactly like one another)
'Similar' means that there is a resemblance between two objects but they are not necessarily identical. For example, if you have a brother or sister you may look similar to them, but you are not identical.
'Same' means that it is not different (like the word identical). If you and your brother have brown hair then you have the same colour hair!
:)