Red Alert 3 has 9 damage types in total: cannon, autocannon, gun, rocket, anti-air, explosion, magnetic storm, prism, and concussion damage. Each unit has different resistances to the various damage types. See the guide in this article for details:
RA3 damage types explained: 1. Cannon 
Autocannon

Gun

Rocket
5. Anti-air 
Explosion
7. Magnetic storm 
Prism
9. Concussion 
Special cases



5. Anti-air 
7. Magnetic storm 
9. Concussion 
