Travel refers to taking a trip or a journey to another place, and tourism refers to the act of traveling as well as to the business side of the travel industry. Travel can also be used to describe the act of moving from one place to the other. Additionally, it is used in basketball to describe what happens if someone takes more than two steps without dribbling the ball.
In some cases, the words can be used interchangeably. For instance, if someone owns a hotel, one could say that he is in the travel or tourism industry. However, tourism is the better choice in this scenario.
Some people draw arbitrary distinctions between these two words. They say that a tourist is someone who visits all of the most popular spots at a certain destination while a traveler is someone who gets off the beaten path.
For instance, a tourist may go see the Eiffel Tower, while a traveler may head to a small country village away from the hordes of people. However, these are not real distinctions, and they are not included in the actual definitions of these words. In both cases, the person doing the traveling is providing money to the tourism industry regardless of whether he is staying in Paris or the countryside.