It's a bit of a stretch trying to categorize all open headphones, because the driver technology is key.
However open designs in general are desired for purist audiophile applications, because it significantly reduces the need to damp the drivers for proper decay and resonance control, as excess energy could largely just escape into the open air rather than get trapped inside the cups.
Which means in general, open headphones done right will have a cleaner sound than their closedback equivalents, better decay, less cup resonance, translates to better transparency because you don't have junk sound waves masking actual music details, and overall a more "open-sounding" signature with more coherent soundstage that doesn't feel artificial.
However the vast majority of performance difference still comes intrinsic with the specific driver types and designs. Namely things like voice-coil dynamics vs planar (electrostatic or magnetic), size of diaphragms, etc.