Final answer:
The Third Crusade sought a naval route to avoid the difficulties of previous overland journeys and complications with the Byzantine Empire, whereas the Fourth Crusade veered off course by attacking Zara and never reached the Holy Land.
Step-by-step explanation:
The route taken by crusaders in the Third Crusade differed from those in the other crusades mainly because they sought a naval path to avoid the problems encountered in the overland journeys through Anatolia and also to circumvent the Byzantine Empire, with which relations had soured.
The Fourth Crusade, prompted by Pope Innocent III, marked a significant deviation as it was diverted from its initial mission. Instead of reaching the Holy Land, the crusaders were redirected to attack Zara, ultimately leading the pope to excommunicate them for this action.
Historically, the First through Fourth Crusades faced various logistic challenges, with the First Crusade being the only one that successfully accomplished its objective of capturing Jerusalem. However, later crusades, including the Third Crusade, only achieved partial success, unable to recapture Jerusalem but managing to negotiate access for Christian pilgrims to the city.