Both Fitbit and Apple Watch can track workouts. However, depending on the actual device you're using, they will do this in very different ways, says Gebbie.
"For example, any device from either company can detect when a user is active and record metrics like heart rate and calories burned to review afterwards. But when it comes to specific forms of exercise, there are some differences.
"If you want to go for a run, you’ll be best served by a wearable with GPS on board to get the most accurate tracking of your movement. All Apple Watches include this, whereas not all Fitbits do."
Owning an Apple Watch allows access to Fitness+, hundreds of instructor-led home workouts including HIIT sessions, yoga and spinning on your iPhone, ipad and Apple TV (but this requires an extra subscription).
You can get workout classes from Fitbit too, but only if you subscribe to Fitbit Premium.