GPX was made for GPS devices and sports trackers, KML for Google Earth visualization. GPX records routes, KML styles them.
| Criteria | GPX | KML |
|---|---|---|
| GPS devices | ✓ | ✗ |
| Google Earth | ✗ | ✓ |
| Styles & colors | ✗ | ✓ |
| Time & speed | ✓ | ✗ |
| Sports apps | ✓ | ✗ |
For Garmin, Strava, Komoot, sports tracks, navigation.
For Google Earth, beautiful presentations, styled maps.