I kinda understand(I think) of your explanation. But I just realized something. When I first got set up with apple. I thought I was supposed to use an @iclould address. I was under that impression I would have my main @yahoo.com acct and @icloud acct. Would've been too confusing at the time. Then someone told me ,no, you can make one with email'. So, I aborted my @icloud acct. and used my @yahoo.com as my main regular email, the same @yahoo.com as my iCloud acct (different passwords).
My problem comes when decided to use use my @icloud.com as another id for other sites. But for some reason when I sign into iCloud with my @yahoo.com, then sign in with my @iCloud.com I get the same account info. I see my in my settings when I sign in with my @icloud.com, I see the info as my @yahoo.com Apple ID .
How is that? Can I separate the @yahoo.com and @icloud.com? Can I make the iCloud.com as a separate acct.?