Few More Inches, Big Difference

So what is the difference between a 26” and 36” soft box made by the same company with every other variable mitigated?

The left image on the larger mod is considerably more open, warmer and softer. Brightness was close to the same (1/2 stop to the little one, but I also aimed it straighter, where the 36” was feathered).

Depth of coverage is also excellent, better than my depth of field!

The smaller one is better for this type of thing though.