What is the difference between developer.paypal.com and x.com?

I thought that I have a developer account at PayPal (still logging in successfully to https://developer.paypal.com), but when clicked the PayPal Developer Network link on that page (to ask a question that's specific to PayPal API), I was prompted to login again. This time, my developer.paypal.com's account userid & 开发者_开发问答password simply wouldn't work there.

Am I supposed to create another account there? If so, will it be linked to the developer.paypal.com one (just as accounts in SO/SE are linked)?

If I may explain my confusion further: I have a "regular" PayPal account (for purchasing stuff online), I have a business account (for accepting online payments), I have a developer account (for testing integration of shopping cart with paypal). How many accounts do I need with PayPal? When I create an x.com account, will it conflict with my existing accounts?

Thanks.

EDIT: What's even more confusing is the question in the login page to x.com:

Already have a PayPal account?

Well, of course I have a PayPal account. In fact, I have 3 of them. Do I need to create another one, just to post a question in the developer network forum?

No, you don't need to create another account. To login to the PayPal Developer Network, you can use either your personal or business PayPal account, but (ironically) not the "developer account".

The https://developer.paypal.com site is for the sandbox only. The https://www.x.com/ site is the actual PayPal Developer Network (tools, API, forums, support, etc.).

Notice the announcement on sandbox homepage:

PayPal Developer Central is moving to x.com