last time, Cain can't identify items.

but now when I played, I noticed now Cain has the option to do it, but we still can identify the items ourselves.

Is there any difference between identifying the items ourselves with Cain?

Haven't played for a long time, so didn't know about this.

Book of Cain identified all items in your inventory

But we still can identify the item ourselves, but one by one of course. Does the book of cain give some bonus when using it other than identify all item in one go?

No. It is just for your convenience.

yup.. all item in 1 go

thanks for the clarification. guess no need to bother then. not like I can get more than 1 legendary item per game anyway and all yellow loot no need identify now.