The range for most diode lasers is +/-10nm. The Nichia diodes are 455nm at a case temp of 26*C I believe, and diodes usually shift wavelength by .3nm/*C, I assume places like Dragon Lasers and CNI just took a mean wavelength.
That would make no sense, you can't tell the difference without very expensive equipment and there's no benefit to labeling it as something 'brighter' when it's only 2nm brighter.
Uhm ..... if Casio diodes are really the Nichia chips in 5,6mm cans, i remember that their first datasheets was specificating "medium wavelenght 445nm" with "minimum 440" and "maximum 455" ..... so, no differences at all ..... is probably just a commercial trick for make the buyers think they are buying something different