Investing is a global activity, so there is often very little difference with regard to many activities (such as how margin works, order types, etc.). The biggest difference, however, is the possible impact of currency on returns. One argument is that currency fluctuations reduce return correlations, so they should not be hedged within a portfolio. Others, however, have recently turned to currency hedged investments to protect against the rising dollar when invested in foreign assets. See article here, Yahoo.
Dolvin, Steven D., "International Investing" (2015). All Chapters. 125.