hardly the same thing. for you to get a stack or two you just need to construct that cheap building which takes 1 turn to build, right? you got 3 of those (and those are call for reinforcements thing aka call for a crusade, essentially the same thing) in 3 different provinces of holy land. the fact that building can only be build in holy land is another prove that it isnt anything other than a call for crusade. Kypchak horde on the other hand is the event they can only happen once and to get it they need to conquer the entire steppe, about 15 regions.
correct me if im wrong.
just trying to figure out what is what so bear with me. i never actually played a prolonged BC SP campaign.