Guided workouts allow you to take your workout plan into the pool or open water by connecting your Swim Trainer app with your smartphone. They are currently available for Fitbit and Garmin smartwatches.
Pool
Pool workouts give you a number of sets with a specific distance.
Open Water
The sets of open water workout do not have a specific distance to swim. Instead they use a timer: after the specified time for a set, your watch starts vibrating to indicate the end of the set.