I have been told that ID protection actually is whois protection when register domain. However,there is "privacy protection" in domain control panel. I wonder whether the said ID protection is equivalent to privacy protection .

I'd guess so, but you'll want to check with whatever control panel you're using. I've heard the terms interchanged, but it's always best to ask whoever you're buying it from, if it's the same thing, or something different just for them.

Well, even I think both are one and the same thing.

I think it is same. They are just the different terms given by different providers.

Privacy protection is pretty much understood to protect WHOIS info, but ID protection could be any number of things (normally)

Got it. Many thanks to you guys.