The difference is the existence and proportion of dark matter has been confirmed across multiple different scales and context, from galaxy rotation curves to th

The difference is the existence and proportion of dark matter has been confirmed across multiple different scales and context, from galaxy rotation curves to the cosmic microwave background to gravitational lensing. We've also found galaxies where dark matter doesn't exist in any measurable quantities. So it'd be more like a couch that's supposed to weight 200 lbs reads 300 lbs on a scale. But we've tested it on a half dozen different scales from different makers and keep getting 300 lbs. In addition we've tested this other couch that's suppose to read 100 lbs on some of these scales, and it correctly reads 100 lbs.