Disclosure refers to the act of saying he's from MS. Disclaimer means that you should read what he says knowing that he might have a bias, because he's from MS.

Disclosure refers to the act of saying he's from MS. Disclaimer means that you should read what he says knowing that he might have a bias, because he's from MS. As they both result in the same thing (you need to read what he says understanding he may be biased), you'll see them both used. I usually use Disclaimer, but there's no real reason for that.