Actually it was an approximation of a quantitative measurement, but let's not get pedantic about it, eh?Actually 57% of the price. You say it offers 90% of the features, but that's a quantitative measurement, of the 90% of features it offers, I'd say qualitatively the R4 does them better, hence the extra cost is worth it.
A hard drive bracket is a hard drive bracket...but the R4's offer SSD fixing points, on removable drive cages, with vibration damping for 3.5" mechanical drives, and are completely toolless, it's the difference between:
FYI the Three Hundred Two offers two SSD specific fixing points (one behind the mobo tray, one in front of the PSU). It also has toolless 3.5 & 5.25 fixings. The only things it lacks over the R4 are the removable drive bays, sound dampening, and the two USB 2 sockets (it has just two USB 3). Hence the 10% approximate difference I don't doubt that the R4 is a good case, I just think the Three Hundred Two offers better value.