using the "site:" what does this mean?

[Craig_F]

I'm seeing 2 different things on 2 different sites that I never noticed before until some posts here made me check it out.

Site #1 - Google shows Results 1 - 2 of about 28,200 results. I can only see the 2 results unless I click the "repeat the search with the omitted results included" link...why is that and what does it mean?

Site #2 - Google shows results similar to the above but a lot of the listings have "Supplemental Result" next to them, does anyone know why that happens with some pages and not others?

Thanks!