I think the bw has a higher brightness rating, though they may have just been measured differently. The only stuff I can find on the 226nw seems to be on Turkish and spanish language websites. I am skeptical because based on the info I've found, it appears to lacka dvi port and comes with only an analog vga connection. I found something about the VAT being significantly lower on vga-only monitors so this appears to be the reason. This site explains it somewhat if you can make sense of the translation or understand spanish.
Translated version of http://marcelosoft.blogspot.com/2007/07/samsung-syncmaster-206226-nw-en-ubuntu.html