benchmark.js is a much more elaborate benchmarking implementation; primary with its support for microtiming ($lt ms intervals) and numerous configuration. it also has support for more javascript environments.

matcha is meant to be a more simplistic approach. less options & readable async tests make useful for quick experimentation and less involved to get started. it currently only supports node.js.

it should be noted that matcha doesn't yet have a browser version, but it's on the roadmap.