This example shows my family room response curve that represents the room’s acoustics. Every room is different in this regard. You can see peaks and dips at specific frequencies. To correct those, an equalizer has to be able to target the frequencies where the peaks/dips occur. Most graphic equalizers are designed to target pre-determined frequencies per band. That kind of equalizer can change the tone of the sound but cannot address a specific room’s acoustics which is a primary factor that distorts what you hear relative to what was recorded. A parametric equalizer can be set to address specific frequencies so that is a better solution. Then you have DSP which provides the ultimate flexibility in changing what you hear. DSP is a computer program that works with digital audio signals and. applies algorithms that can automatically determine what needs to change and then create the specific equalization and apply it to the digital audio signal to adjust it for the room. Whereas with a traditional graphic equalizer you can adjust specific frequencies but you cannot do that in a manner that properly addresses the variations that a specific rooms acoustics creates. Hope this helps to understand the differences.