I think one way of interpreting the poem is to say that he took the less traveled road both figuratively and literally. In life, he chose to do things that other people were not doing. You can interpret the "difference" he says it has made in his life as either positive or negative, but most people assume it is positive.
We all make certain choices in life. Some of those choices make life harder, and some make it easier. For example: You have a choice whether to go to college or start working after high school. That choice will affect the type of job you can get ,the amount of money you will make during a lifetime, and your lifestyle. It may even affect the type of woman you marry. That one choice made "the difference" in what your life was like. In the poem, the poet has a choice of traveling on two roads. He took the one that was "grassy and wanted wear" -- but they had both been worn about the same. It would be nice if we could see what going to college and/or starting a job after high school BOTH would do for us, but we can't. Even the poet says that "knowing how way leads on to way, i doubted I should ever come back." to travel the other path. The choice he made, made a difference in his life. Another choice might be if you want to join a gang or go your own way. That choice would definitely affect your behavior. Choices introduce us to people from different areas of life and the world, and our contact with them will affect how we behave towards others.