> For example, if you connect to WiFi, Android will recognize it as a non-mobile network, and start doing updates, etc. If you start listening to a song via Pla

> For example, if you connect to WiFi, Android will recognize it as a non-mobile network, and start doing updates, etc. If you start listening to a song via Play Music on WiFi, and then go out of range, it will automatically downgrade the quality, or stop playing and ask you if you want to continue. Since the wi-fi radio is different from the cellular data radio in the phone, it's trivial to set different policies depending on which radio the phone is using. The settings to allow differentiation exist because we know implicitly that a wi-fi connection won't be draining your expensive data plan. The phone doesn't actually look at a connection's bandwidth/signal quality/etc to do this.