It kinda is. (And why I didn't buy it at release.) Vanilla Beyond the Sword (2nd expansion) Civ IV had 92 techs, expansions Civ V as 80. IV is sort of like the 3.x to V's 4E (but not quite that drastic).
Incidently, I recommend instead of a pony mod (as the only one out there isn't as completed even as the Civ V one, so you're not missing much, and the leaders wrok differently, so they don't have completely unique traits as standard), you play the NextWar BTS mod as a normal game (as that basically adds the sci-fi units to the end of the regular tech tree) - if you can find a pony mod FOR NextWar (and you probably can!) even better. (Though non-official mods for Civ IV have to be installed manually, rather than in-game, which is something Civ V is done better.