Your professor may be looking for a specific textbook answer we are not privy to, but I can help you with the fundamental differences and similarities.
1) Cultural differences - most foreigners do not watch as much television as we do, and they tend to read more, so the approach you take with marketing has to fucntion in a different media model.
2) Language - of course, marketing fluent in the local languages is a must, and sometimes in multiple languages. Nuance matters, as does subtlety. What is unoffensive and humorous in our language sometimes translates into something completely different. There was the famous Chevrolet disaster of marketing the Chevy Nova in Mexico - "No va" meaning, it doesn't go in Spanish.
3) Buying habits - Many people in foreign countries do not have refrigeration as it is very expensive, so they tend to shop every day, and buy smaller quantities. Costco-Europe, for example would have a hard time being successful, as people just don't shop in huge quantities like that. In many other countries, there isn't the buying power in terms of economic strength to do so.
1) Materialism is nearly universal - what motivates buyers in the US often motivates humans everywhere - to find a convenience, to rest and recreate, to be fashionable and popular. So the underlying motivations for the individual economic behavior of a human is the same almost anywhere.
2) Price consciousness - All humans, not just Americans, want to get the best deal possible. They often react to sales and sales prices in the same manner - by buying more. Marketing has to be adjusted to reach the audience, but many of the basic tenets are the same.
3) Demographics - I think you'd find that marketing techniques that are successful in the states with the under 18 demographic are successful in many places, and the same could be said of the senior citizen demographic. Cultural differences exist, to be sure, but marketing toys to young kids and medicine to senior citizens is bound to find some success in any market.
International marketing is quite different from that of marketing within the US only.
In international marketing the enterprise has to first consider whether the product that it wants to market is something that will have a sufficient number of customers internationally, and this will vary for each country. A product that is very successful in the US may receive lukewarm response in some countries and fail entirely in others.
In addition the marketing strategy has to be appropriate for the market that is being targeted. The culture and customs of other nations and the people the enterprise is targeting have to be kept in mind while creating advertisements and in many cases the product itself may need to be modified. The marketing medium also has to be chosen appropriately. The internet may be a great medium in the US but in a nation with a very low internet penetration it wouldn't work.
These are just some examples of the factors that have to be considered. There are many more and each has to be considered.