I have a question about GPG

[FanEagle]

Ok, i had this nightmare about people impersonating me to do bad stuff... so i woke up and furiously searched about gpg and found a couple tutorials that teached me fast how sends messages and decrypt.
Problem comes when I searched for someone very recognized on this forum gpg and found weird about not a true pgp code but the key.
Ok then, I searched how import it in gpg4win and successfully did it, giving me all the infos about that public gpg, the issue I found is the difference between the key the program offers me for any key I have and the one I found on site.
Let me be more effective: the key ID I have is 8 lenght, meanwhile the key id of the person I won't say it's on bitcoin-otc and that key is: 16 lenght
Now, where the hell they come from the initial 8 chars because the key the application recognize(perfectly I must say) it only sees the last 8 chars.
Did I missed something or the 8 chars identifies even the bitcoin address somehow?
It's the only thing that comes in mind, and if that's the case, how can I add it to my keyID? is it referred to the optional comment the application talks about?
Thanks.