2.4Ghz WiFi devices (i.e., 802.11b and g) in the US and Canada may use channels 1 through 11 only. The EU allows channels 12 and 13, and Japan allows 14 too. If you brought over a Japanese model adapter and tried to use channel 14, it wouldn't work. If you brought over a Japanese model access point and put it on channel 14 too, thinking that would not only make it work but in addition fly above the interference from all the other channel 1-11 devices in the neighborhood, well that would be against the law and could cause all kinds of other legal problems if you interfered with something else that has legitimate authority for the specific frequencies used by channels 12, 13, or 14 in the US/CA.
But this is all information for your entertainment. Bob already answered your question.