The reason for the time-differences between Congress and Senate elections is so that each house may control the dictatorship of the majority? The elections are held at exactly the same time - or do you mean term durations? It is supposedly so that there is one part of Congress that is immediately responsive to the desires of their constituents - because they have to face those people every two years - and another that has the ability to take a longer view. In practical terms, that is how it usually works...that is, there are a lot of strange bills that are introduced (or even passed) in the House to placate those back home that never even get introduced in the Senate.

What, BTW, does "dictatorship of the majority" mean? The majority always wields dictatorial powers in a democracy, although they may not always act like it. That is one of the most basic definitions of a democracy.