This is a good question but the problem is that it's a combination of different things. The brand of print heads being used in the machine, the quality of those print heads, the number of passes being executed, inks and, of course, the DPI.
Depending on the combination of those factors, you can get drastically different quality outputs.
Should some value speed above all else, they'll change the printer to what is most often referred to as 'production mode' which is going to be a lowered ink output along with low passes. This reduces the amount in ink output and the number of times the print head has to pass over the media to lay down enough ink to be considered 'passable'.