nope, no big deal... the write-ups on the sites were so close, including the part about spraying electronic parts, that I had to wonder. makes it easier if it is the same, as it can be bought through Amsoil!
I've used three of the above - never tried regular Amsoil MP.
The regular CorrosionX is a clear liquid. It's somewhat viscous, but it doesn't dry and remains liquid. I use it on my firearms for long term protection and love it. We use it at work as well. No cleaning is required between storage and use of the item its applied to.
CorrosionX HD dries to a clear, waxy, as someone above said, slimy substance. It's a lot like LPS3 - a soft, waxy coating. I like it for long term protection. It does need to be cleaned off before use.
Amsoil MPHD dries to a tough, brownish/yellow coating. It's a very long-term protectant and is very tough to remove. Perfect for underbody coating, etc... This is tough stuff. I use it on bumpers, hitch balls, etc...
I'd bet dollars to doughnuts that MPHD is a repacked CorrosionX product called MaxWax. It smells, looks, and dries to the same hard coating as the MPHD. I like them both.