The one on the left...... the handset decoupled and you plugged that into the car. The "box* went in the boot. Back to a fixed car phone. Was known in the trade as a "transportable".
Jump forward a little and we get to "pocket" phones. Then to smart phone, then to full blown computer in your hand.
The one on the right is my new one. A Nokia. Again. Only this is a phone. Just a phone. It makes and receives calls. Can send texts too. Even has a radio built in. Oh and a camera. A few games pre installed but in reality it's just a phone.