Look at it this way: You have a Google account, possibly made with a GMail or maybe with a Hotmail email address. It is your management account for all things Google. And YouTube is (since 2006) Google's premier video sharing facility or "service". Blogger their service for blogs and Picasa is Google's photo storage/sharing service. Etc etc.
For each of the services you need a public name which is outward facing, which is your "nickname" in that community. At YouTube this takes the form of a YouTube channel- which lets you upload, add favourited videos to playlists and, in your case, network with other YouTubers.
Since your Google account username is your email address and you shouldn't have all the world and sundry know it, you get to pick an anonymous username at YouTube, what you wish to be known as.
And this place, the Google forum for YouTube, is another site altogether- one which ALSO doesn't encourage you to reveal the true name of your Google account (ie email) and invites you to have a forum nickname.
So- one YouTube channel which you name, a Google account which IS named for your email address and a forum nickname too.