Greetings, Jeff P.
I see that you're wondering about the difference between a walk and a hike using your Apple Watch. I'm happy to help.
About workout types -- These are the explanations that Apple provides.
Choose Indoor Walk for walking on a treadmill or for when you're walking indoors, like on an indoor track or in a mall. To improve the accuracy of pace and distance for Indoor Walk, first accumulate at least 20 minutes of outdoor walking using the Workout app to calibrate your watch. For Apple Watch Series 1 or earlier, you need to bring your iPhone along for calibration.
Choose Outdoor Walk for activities like walking on a track or in the park. Depending on your Apple Watch, you might need to bring your iPhone with you to track certain metrics:
- Pace and distance: Apple Watch Series 2 or later has built-in GPS to track these metrics and provide a map of your walk in the workout summary on your iPhone. For Apple Watch Series 1 or earlier, bring your iPhone along for GPS. If you want to leave your iPhone behind with Apple Watch Series 1 or earlier, you can still track pace and distance for your workout. To improve the accuracy of these metrics, first bring your iPhone along and accumulate at least 20 minutes of outdoor walking using the Workout app to calibrate your watch.
- Elevation: Apple Watch Series 3 or later has a built-in altimeter to track this metric. For Apple Watch Series 2 or earlier, bring your iPhone along to track your elevation.
And
Choose Hiking to track pace, distance, elevation gain, and calories burned. You can see how high you’ve climbed in real time during the workout, and total elevation gain at the end of your workout.
Apple Watch Series 3 or later has a built-in altimeter to calculate and display your elevation, so you don't need to bring your iPhone along when you work out. For Apple Watch Series 2 or earlier, bring your iPhone along to track your elevation.
Take care!