rebuilding and rebalance is different or same? (sc8000)

First of all, my english is not that great. Please cut me some slack (is this right??)

Recently I am managing sc200 and found a down disk the other day.

Before replacing the disk, there is no word for rebuilding in the sc series documents. However, there is a word rebalance in the sc series documents.

I think two word ( rebalance and rebuilding ) mean same.

Please answer!

Thank you for reading terrible english.