If I recall correctly, catégorie C (and D) are the U19 variations and are two separate Tomes.
Short on-line summary of main variations
Stuff like, not allowed to sack the line out jumper under any circumstances, even once his feet are back on the ground - i.e. no tackle allowed before maul is formed. Temporary exclusion is only 5 minutes at U14. Any brutality means player can take no further part in any matchs that day.