Explain why echopraxia is described as differing from ordinary social mimicry, even though both involve copying another person's actions.

Ordinary social mimicry is a normal, largely voluntary behaviour people use, often without much thought, to build rapport or express connection with someone else — and people can generally stop doing it if asked. Echopraxia has an automatic, seemingly compulsive quality: the patient typically continues imitating even when it serves no social purpose, and may show no awareness that they are doing it at all. The behaviour looks superficially similar from the outside, but the voluntary, purposeful quality of ordinary mimicry is exactly what's missing in echopraxia.