crop sensor eos bodies slightly range in size?

[recon photography]

i found this on my interweb travels http://snapsort.com/compare/Canon_EOS_1000D-vs-Canon_EOS_550D
it seems to say that a 550d sensor is a tiny bit larger than a 1000d does any1 know about the other bodies is one of these just a one off? Whilst on the topic does a crop sensor for canon crop to exactly 1.6 or are there a couple numbers left out?

 

[WarStreet]

The digital picture have a good list of different sensor sizes.

http://www.the-digital-picture.com/Reviews/Canon-EOS-Rebel-T2i-550D-Digital-SLR-Camera-Review.aspx