Explanation regarding "init",Full Repair Request","Full Update"

HI Guru's,

I need clarification about the following things.

While doing backfilling we will do either Full update or Full Repair Request or Delta Update.

I want to clarify myself when we have to for the following Update methods.

1.Init without data transfer.

2.Full repair Request

3.Full Update

4.Delta update.

with some scenorio will be appreciated.

Thanks&Regards,

Gowri