What's the difference between a milestone and an accomplishment?

A milestone represents a (very significant) step along the way; an accomplishment is a triumph in and of itself, even when it is also a milestone on the way to something else…


They are sometimes used as synonyms, however a milestone is a great accomplishment.

A milestone is more significant than an accomplishment. You accomplish something when you finish it. I accomplished combing my hair this morning. I wouldn't call it a milestone.

But don't just take my word for it:

According to Merriam-Webster online an accomplishment is "the act or fact of accomplishing something."

Alternatively,

According to Merriam-Webster online a milestone is "a significant point in development", such as graduating from college.