Templars are the preachy "Oh you don't want to embrace the word of god? That's ok, i'm sure you'll find your own path to paradise in the afterlife"
Inquisitors are the "If you don't bow to the will of Cazic-Thule he'll [expletive haxx0red by Raijinn] you to eternal hell" And then if they don't give in to the Inquisitor's faith, the Inquisitor tortures them until they die or give in.
Needless to say, Inquisitors are much more common in the history of Earth.