What you asked for has nothing to do with what you want to know.
You asked for transmission speed but what you are trying to understand is the difference in stability of a wifi link. This is way more complicated than the simple Mpbs figure you asked for.
If you really want to understand whats going on you need dedicated RF equipment and knowledge about very complicated matters. Stuff like link saturation, collision avoidance, signal to noise ratios, sensitivity, frequency tuning of antennas, transmission power, antenna polarization, radiation patterns, ... come to my mind. Plus a hundred other things
And I'm no expert for this domain. Lets say: I know enough about this to understand that I know nothing. Certainly not enough to jump to conclusions.