The poet says I took the one less travelled by, And that has made all the difference. What is the difference that the poet mentions here?

The poet says that he had encountered a fork in his path , that refers to the important choices of one 's life, the decision that determined his destiny. He says that he took the road less travelled by, that is he took the less taken choice, he chose the less chosen path for his life and that made a difference in his life.

The difference in his destiny was that it was unique and set-apart from the other 's and in the end it proved to be a better choice.

HOPE THIS HELPS.... :-D