Following on from my last post, I thought it was fascinating to see Gordon Brown using the word "multilateralism" together with "opportunity". A socialist would have said "internationalism" rather than "multilateralism" in this context, which as international relations and the new US president.

So, for some definitions:

Multilateralism ( http://www.merriam-webster.com/dictionary/multilateralism ) :

1 : having many sides
2 : involving or participated in by more than two nations or parties <multilateral agreements>

Internationalism ( http://www.merriam-webster.com/dictionary/internationalism )

1: international character, principles, interests, or outlook

2 a: a policy of cooperation among nations
2 b: an attitude or belief favoring such a policy

If you try a few other dictionaries, you will find slightly different definitions for internationalism that emphasize cooperation and/or solidarity between participants. But let's stick with the Merriam-Webster one for now.

The big difference between multilateralism and internationalism is cooperation. Multilateralism leads to negotiation and  deals between parties. Internationalism leads to cooperation towards common goals. Similar, but by no means not the same.

An example of multilateralism is GATT (the General Agreement on Tariffs and Trade).
An example of internationalism is the United Nations Universal Declaration of Human Rights.

I'm not saying one term is better than the other, only that it illuminates Gordon Brown's world view; and his view is one of haggling, deals and compromises, not one of principle and shared ideals. I don't know if that makes him a realist or a cynic, but it certainly doesn't make him much of a visionary.