Yes and No.
The real answer is no. Your Google user name is just the first part of your email address. For example, if your email address is
v8vega@gmail.com or
v8vega@googlemail.com, your Google user name is "v8vega".
However, Google allows you to log in with your gmail address in place of your google user name in most applications. There's a lot of fragmentation across the Google ecosystem so on some applications this may not be the case, but for the vast majority it is.
So, yes, you can use your gmail address and password to log in. The password for your gmail and your Google account is the same.