I have always, once joined to the domain, logged in to that domain with simply the username and password. In a new office I recently started working at they are logging into the domain using username@domain.name after typing the @ sign the select domain drop down changes to greyed out and displays "Computername - this computer" as the domain to login to. So heres my question, is there anything different with logging in that way versus the normal way? as far as policys, local computer settings, and probably most important is profile creation. This seems like a very sloppy login method and havent been able to find any information reguarding it, any help would be great

you can do it either way

The login names your more familiar with are netbios names. The user id that looks like an email address is a UPN (User Principal Name) and is used commonly in environements that have multiple domains within a forest. If a user is a member of one domain let's say 123.xyz.com wants to login to another domain in the forest like sales.123.xyz.com then they could use the UPN name. The grass may not be greener on the other side but it sure does have less weeds.