Some general information on the many types of terrain encountered on the more popular routes on the Camino de Santiago:
The Via Podiensis or the Le Puy Route extends approximately 690 km across southwest France to the French-Spanish border and is famous for its beautiful terrain and architecture. The route begins in the high plateaus of the Massif Central which involves steep climbs through woodland and villages.
After leaving the Massif Central, the route includes long walks through agricultural land, open grassland, and vineyards and along rivers and canals. In the French Basque region the terrain becomes mountainous upon approaching the Pyrenees and the start of the Camino Frances.
Although this walk contains long stretches of easy walks, the rugged, mountainous regions with long, steep climbs and descents make it a challenging but rewarding walk.
See link below for types of terrain on other popular routes: