How do you determine if you're using Wi-Fi or LTE? On Android, how do you tell if you're connected through Wi-Fi or some other type of connection like LTE or 3G? 

If I'm sitting at a Starbucks and I sign-in to their Wi-Fi, my phone has both the Wi-Fi and LTE icons showing. How do I know which connection I'm using? 

When I'm at a place that has Wi-Fi, I want to use Wi-Fi and not my data from my data plan. Is there a place in Android that specifically tells you?
There isn't a specific place that it shows, but the WiFi connection will take priority over the cellular data. If you wanted, you could perform a SpeedTest to check your service provider, but that shouldn't be necessary.

Also, if you're worried about updates and whatnot using your cellular, the downloads will initiate on WiFi (if you have that option) but they will continue on cellular if you lose the signal.