I don't see an equivalency. Low Earth Orbit satellites are above the ionosphere, balloons below. I suspect if it is radio traffic that you are interested in listening in on then one of those is much more effective.
LEO satellites are great for RF reconnaissance for frequencies between 100MHz and 100GHz which easily penetrate the ionosphere. They can even geolocate the source on the ground by measuring the observed Doppler shift (caused by the spy satellites own fast motion)
