OverlayThis is a free plugin that easily lets you compare the data tracks, routes and summary values or two or more activities.
Data tracks of the selected activities are presented in the same graph so that you may visually see how well your form is progressing. You can show heart rate, speed, pace, power, cadence, elevation, distance and time.
The routes of the activities are shown on the map.
The summary numeric values can be compared in a table.
The table and chart can also directly present the difference between each activity and a reference activity.
Integration between Overlay and the Unique Routes plugin allow the user to extend the activity selection with other activities on a similar route.
See plugin homepage for more information