US Vs Canadian Travel

As previously mentioned my mom's Canadian Citizenship was retroactively restored to her (as of April 2009) and she got her Canadian Passport today. She now has both an American and Canadian Passport. We have all heard that Americans travelling overseas usually get treated badly because of Anti-Americanism and that no one ever harasses a Canadian. Only once when I was in Russia did I tell someone that I was Canadian - when I did it shut them up about everything they considered bad coming from the US. Every country has their good and their bad aspects, but it seems that people around the world only see the bad in the US - I think it makes them feel better knowing that a country as great as the United States has flaws.

Wikipedia says that US Passport holders can enter 155 countries without visas or by getting a free visa on arrival while Canadian Passport holders can enter 150 countries without visas.

The United States has an Embassy and/or a diplomatic presence in almost every country (except for North Korea and Iran) while Canada has many countries with no Embassy or direct diplomatic presence. The paper that came with the Canadian Passport says that certain countries are handled by the Australians and others with the British.

I'm curious to learn more about the differences in travelling with the two passports.