From what I understand the black filters are more effective on a wider variety of contaminants (and more expensive). I've also noticed more US retailers are only offering the Black filters.
The powerful Black Berkey® purification elements also remove or reduce pathogenic cysts, parasites, harmful or unwanted chemicals such as herbicides and pesticides, VOCs, detergents, organic solvents, trihalomethanes, cloudiness, silt, sediment, nitrates, nitrites, heavy metals, foul tastes and odors, yet they leave in the healthful and beneficial minerals that your body needs.
http://www.berkeyfilter.com/black_berkey.htmlWhite Ceramic Filters say nothing about removing detergents, solvents, etc. From Jamesfilter.com:
Flow rate is 1 gallon per hour, each filter.
Filter Life is a minimum of 2000 gallons per filter
The filtration efficiency is 0.9 micron absolute (Spectrum Labs)
Removal of >99.99% of particals larger than 0.5 microns (Spectrum Labs)
Removal of >99.70% of particals larger than 0.3 microns (Spectrum Labs)
Removal of >98% of particals larger than 0.2 microns (Spectrum Labs)
100% removal of Giardia
100% removal of Live Cryptosporidium (University of Arizona)
>99.99% Removal of Cryptosporidium (NSF Standard 53 A.C Fines dust-4 log challenge)
>99.99% removal of E.Coli, Vibrio Cholera (Hyder Labs-U.K)
>99.999% removal of Salmonella Typhii, Shigella Disenteria, Klebsiella Terrigena (hyder Labs-U.K)
British Berkefeld ceramic elements May be cleaned 100 times or more
http://www.jamesfilter.com/index.asp?PageAction=VIEWPROD&ProdID=27