I think the difference is are they people asking in a relationship or not - asking which app is categorically asking where they can find someone to hook up with.
I don't know if anyone who's asked me has started using the app as a result, but I think it (anecdotally, again) supports an idea that a successful results for one app organically helps its name recognition.
Edit: unless you meant the difference was between people asking which app vs which spouse.