This poem is an example of an extended metaphor.
A metaphor is a comparison between two things that are not alike. In this case, a road and life are being compared. In this extended metaphor, the speaker never actually makes a direct comparison between life and the road. In other words, he does not say life is a road. Yet the entire poem implies it.
Two roads diverged in a wood, and I--
I took...
Perfectly good used a hyphen incorrectly
