Come on now. The difference between those fences or walls and Israel's version is the location. The US did not build their fence on the Mexican side of their shared border, and the same even applies for the other fences that are located in unresolved conflict zones such as Cyprus or the Koreas. Israel's version would have been deemed a whole lot more legitimate had it been built on the Israeli side of the Green Line.
US rally shows support for ex-Marine held by Iran on spying charges (AP)
from the article: Occupation tourism: A new trend at West Bank fence protest