I have my textbook definition/answer for this, however, can anyone elaborate on it? I have my midterm tomorrow and was hoping to get a new perspective.

What was the difference between the vision put forward by the utopian socialists and that of Karl Marx?

Utopian socialists took much time and effort to imagine a new and better society (in regards to 18th and 19th standards), but they never had a single clue on how to build them, other than relying on the good will of rich men.
Marx' work is mainly to analyze the existing economic's relationships to understand how a new world could actually be built from them.

What is your current line of sight on this question ?