The US is richer, and has a larger GDP as of now (post Dollar run and Euro drop) than the European Union. The US has about ~40% of all private wealth (globally private wealth is around $270 trillion, with US households holding $86 trillion [1] of that; then furthering that are US corporate assets, which are far larger than European corporate assets).
By comparison private wealth in all of Europe is about $60 to $65 trillion. [2]