what is the difference between apple.com and appleid.co

The second one just redirects you to https://appleid.apple.com/ where you can sign into account management. It is good to be leery of potential phishing but in this case I went to that URL, didn't sign in, and then when I cam back here I had to log in again. That's typical behavior for Apple when I try to visit certain pages. If I don't try to log in when they ask me to then I get kicked off here too. Anyway, to me that indicates it is a real Apple page.