The difference is Redknapp took over a struggling, underperforming side not peforming to the sum of its parts and turned our league form around very quickly and got us into the top 4 just 18 months later, whilst also playing the most exciting brand of football in the league, as much as people dislike him, I would be very interested to see people argue this point about the style of play. AVB came into the club that had finished 4th and despite losing key players, were a shoe in for the top 6 at the minimum, which he achieved.
AVB also came to Spurs having underperformed big style of one of our top clubs and being an unproven commodity in England, he had achieved nothing in England. Redknapp was brought in to get us out of trouble, he wasn't a long term appointment IMO, he has taken teams down, but he has also kept teams up after relegation battles. The Spurs job represented his first crack at a "top club". AVB had already been given a chance at a top club in England, but he squandered it.