Defense is a catchall term that applies to both armor (physical damage defense) and resistance (special damage defense) just like offense is a catchall term for both physical and special damage.
And, as stated above, T3 doubles his own armor and resistance penetration before handing that number out to all droids (including himself) so after all is said and done, he will end up with a total 4 times the number you see in panel for Armor and resistance penetration while all other droids will receive double his in panel numbers.