What is the essential difference between a single supply op amp and a dual supply?
The key difference is that single-supply op amps will accommodate input voltages and drive output voltages that are very near to the power supplies. This is necessary to preserve dynamic range since the voltage swing is smaller. Single-supply op amps can also work just as well with a dual-supply. In order to accommodate single supplies, these op amps are often designed with complex stages that may compromise on performance, especially distortion. Dual-supply op amps are generally better for industrial applications that have larger power supplies and input levels, and they also typically offer somewhat better performance.