> according to piwik my website had 23% more visitors than on GA A fair share of that is probably because GA is much better at identifying the same user across

> according to piwik my website had 23% more visitors than on GA A fair share of that is probably because GA is much better at identifying the same user across multiple browsers / devices. If they identify two browsers as the same person on site A, they can know they're the same person on site B, even if site B on its own doesn't have enough to figure it out (so piwik can't know it).