Cotton is the brighter, whiter white. Colonial White is a creamier white if I recall.

Call Toto Customer Support in Georgia, 1-888-295-8134, and ask them to send you a sample of each. I did it 5 years ago and the nice lady sent them free of charge.

Thanks napagirl! would have never thought to call them.

cat mom that is kinda what I figured, good to know tho :)

If you search online you can also find which of the 2 whites matches kohler white, or other ceramic whites, if you have other fixtures you are hoping to match. (like the bathtub).