Hello Rio. This is London! Or as we say here in cosmopolitan Peckham, Bonjourno!
There were swords being drawn over this debate on thinkbroadband.
VDSL2 G993.2 Annex A is for the 'Merkins, the Canucks (and.. maybe.. the good people of Ibero-America?)
VDSL2 G993.2 Annex B is for the Europods, including the Blightyites.
However it's not quite so clear-cut as that because there is a tie-over where some bandplans and power spectrum density (PSD) masks for VDSL2 Annex A and Annex B are the same.
For example, VDSL2 Annex B Plan B (aka Bandplan G.998) used by BT Openreach for its Profile 17a service is compatible with G993.2 Annex A for the Americas (an Annex with only one bandplan).
However, the BT Openreach Profile 8c service is different. It uses G993.2 Annex B Plan A (aka Bandplan G.997) which is not compatible with, for example, the Profile 8a service from the North American telco Qwest.
See:
ITU G.993.2 Recommendations (02/2006) - page 202 onwards.. [1]
cheers, a
P.S. Just to complicate things even further, the bandplans defined in the Annexes for ADSL[1|2|2+] are different to those for VDSL2.
[1]
http://www.home.surewest.net/hyoung/T-REC-G.993.2-200602-I!!PDF-E.pdf