Well Rocker, I didn't copy and paste anything. If you check the NAA website it explains the differences clearly. The .32acp NAA Guardian only fires the .32acp load. The NAA .32 fires a .32 caliber bullet out of a necked down .380acp case. The reason you can't fire the .32acp in the NAA .32 is due to the case size. The barrel is designed to support the .380 case and the section of the barrel that actually holds/fires the bullet is .32. You could put a .32acp bullet into your NAA .32 but the case wouldn't be supported and it's very likely the unsupported case would rupture, destroying the pistol and likely would injure you.
I think the point of manufacturing those three models is simply because "they can". People look for a nitch market. One that will entice buyers. Basically the NAA.32 is a faster, more powerful round. Here's a few numbers that describe that difference.
Remington .32acp 71gr. 950 fps 129 ft/lbs
Corbon .32acp 60gr. 1150 fps 141 ft/lbs
Federal .32acp 65gr. 925 fps 123 ft/lbs
Federal .32acp 71gr. 900 fps 128 ft/lbs
Corbon NAA .32 60gr. 1222 fps 199 ft/lbs
Federal .380acp 95gr. 980 fps 203 ft/lbs
Here's a good website that will provide information:
http://www.handgunsmag.com/ammunition/32_0924/
In the end, you're being given several pistols that perform well and in multiple models. It may not make sense to you that they manufacture several mouseguns in varying calibers and sizes but believe me, it matters to someone or they wouldn't do it. It has been a real learning experience looking up this information for you! Just because you have purchased a pistol that has a proprietary load shouldn't upset you. After reading so much about it, I believe you've got your hands on a real firecracker! It may be expensive to shoot and practice with but seriously, you're not going to be using this pistol for plinking, are you? It's a concealed carry pistol and I think you have a good one.