Size-wise they're very similar. Quality-wise, I'll take the Vision V-70 over the Iris CB-70 any day of the week (and I have both).
I've always had good luck and good prices when ordering from LLL: http://www.lllreptile.com/products/7...70-plastic-tub.
EDIT: As Deb said, there is a slight difference in height. The V-70 is just enough shorter that it would allow for escapees in a rack designed for a CB-70 (again, speaking from experience).