Right from Stihl USA
I contacted Stihl because so many guys were saying their 044's were Magnums but didn't know what that meant. Here is the response:
The 044 and 044M do have the same displacement (70.7ccs)and make the same amount of power (5.4HP). The difference is the decompression valve and the crankshaft was changed to incorporate a larger wrist pin.
All 046s were Magnums.
When I asked if an 044 does not have a decompression button, it is not a Magnum - he said:
That would be a correct statement
Guess most of those "Magnums" out there are just regular 044's with the $5 eBay sticker on them.