There are a several main base types: Hybrid, Defense, and Offense.
Hybrid bases have a good combination of defense and attacking capabilities. They can defend against most attacks, unless teams of tanks are attempting to kill you at the same time.
Defensive bases only contain turrets and strong walls. The unit to defend is to use the commander. They can defend against many attacks and can even be used to attack. But that is their only unit, so this is a defensive base.
Attacking bases are purely offensive or have little amount of defenses. They are weak against huge hordes of attackers! These bases are vulnerable to mass attackers who team up or spread their troops out around the base. Their only defense is to use their many troops.