The Progressive Movement was more successful because it "fit" with society in the 1890's. Society in the 1890's was the industial, urban, and corrupt government. It was the embodiment of the Progressive Movement because that it was it set out to change; corrupt government, working conditions ect. But the Populist movement was agrarian (farm like) and wasn't going on in the time period. Industrialisation was happening, and farming was pushed to the backburner. IT's often said that people only care about something when it happens to them, and that was the Progressive Movement. More people were factory workers than rural farmers, so they cared about the movement that affected them.
I hope this helps if you need more ... let me know
