The Fitbit Charge 4 looks almost identical to its predecessor, including the grayscale touchscreen, but the addition of built-in GPS makes a huge difference, and helps make it a viable alternative to fully-fledged running watches if you enjoy working out for fun and health, but don't need a torrent...
No price increase from Charge 3; Built-in GPS; Heart rate zone tracking
Monochrome display; No design update