Difference In Braun Toothbrushes Differences Between Braun Oral-B 7400 And 9400 Toothbrushes?

Differences between Braun Oral-B 7400 and 9400 Toothbrushes? - difference in braun toothbrushes

Does anybody know the differences between the two? I only know, Oral-B 9400 (~ $ 55) is younger than I expect to be better and high-tech teeth. Also, Oral-B 7400 is cheaper ($ 35), but I think it is always good. It is therefore an opportunity cost. What should I choose, suggestions?