FFF,
Here's an extract from the FAA website, which should clarify things:
Also, any limitations that appear on the foreign pilot certificate are limitations that apply to the U.S. certificate that is obtained under FAR 61.75. For example, some foreign aviation authorities do not allow night flying. That means a U.S. certificate issued on the basis of that certificate could not be used at night in the U.S.
Can read the full version at
http://www.awp.faa.gov/fsdo/foreign.htm
Cheers
EA