What do you mean, not the same? It depends on the provisions of the treaty. It is constitutionally permitted for the U.S. to agree to treaties which limit what we would otherwise have the sovereign right to do. I suspect there is no treaty written that does not limit our government's actions in one way or another. I presume that the establishment of the U.N. in the first place involved our signing a treaty. I'm not saying that we have signed any treaties that require us to get the U.N.'s permission to go to war, but if we did, there is nothing in the Constitution to prohibit it. Notice also that as written, the Constitution appears to give treaties equal status to itself and federal law in being the supreme law of the land.
As for breaking a treaty, all laws, including the Constitution itself, can be repealed.