I've been looking at the Eldritch knight prestige class and i was wondering, why does it even exist? The magus class is basically everything the Eldritch knight is,except the diverse training. So, am i missing something?
Yes. The EK has full access to the wizard and sorcerer spell list, including 9th level spells.
EK is also a prestige class adapted from 3rd edition long before the Magus was introduced.