It's the same thing. I wrote "International" assuming that not everybody reading this post would be in the United States, and the idea is always to donate to your own country's national chapter of the Red Cross first. The American Red Cross is sending funds and resources directly to Japan, as are many other national chapters of the Red Cross.

If you want to donate money directly to the Red Cross of Japan you can find steps to do so on this page (http://www.jrc.or.jp/english/relief/l4/Vcms4_00002070.html), but personally I think it's a better idea just to donate to your national Red Cross chapter.