He mentioned ballistics gel tests were within inches of each other on penetration.
One thing to make sure you are accounting for with such tests is whether it is an apples to apples comparison. Factors that can make it apples to oranges include: barrel lengths, bullet construction, bullet weights and velocities of the loads vis-a-vis the full potential in the cartridge. Its also important to make sure the gel is calibrated. If not a comparison doesn't mean much at all.
An extreme example of all of this would be an 80 grain 9x19 glasser safety slug with a light charge fired from a Rohrbaugh R9 compared to a 100 grain hard cast buffalo bore +P .380 round fired from a Glock 25.
I don't think what they are comparing is as extreme as the above, in fact I have long argued that guns like the R9 with very short barrels have little if any real advantage over some of the 380 options when comparing terminal ballistics and the accompanying trade offs to get such a small 9x19. That said, I want to see the test in question before I believe the are too meaningful.