YouTube quality sometimes really great quality dilemma

I have a question that I just don't understand. Important to note that a don't know much about this stuff. Sometimes when I listen to music on demo for speakers or reviews and play it on any of my speakers at home or in the car it sounds amazing with great clarity definition. It is like a whole new system. Now I will use my car for this example. When I listen to the radio it sounds like a radio. When I listen to CDs it's better for sure. When I stream off my phone through Bluetooth it's in-between depending on music. I can use Spotify, tidal or qobuz and they are similar. When I listen to a great recording on YouTube throught the phone and Bluetooth it can be downright amazing. Like the difference between a Bluetooth speaker and HiFi speakers towers difference. I don't understand how that can happen. No muddiness super clean. If my Bluetooth on my phone without WiFi can't play hi res music then how come YouTube through Bluetooth and my phone sound like great hi res music on a great system. Please help me understand what is happening. Thank you , jay