[Samsung Galaxy S7 Questions and Answers] phreich:
The hardware is NOT the same -- firmware is incompatible:

I don't think you can successfully flash the North American Qualcomm based firmware onto the Exynos hardware or vice-versa. At best it would give you an error, at worst it could brick the device. They are two completely different processors on different motherboards, and use different other hardware as well (power regulation chips, radio chips, etc).

What may have happened is that someone found a way to overwrite the model number and/or possibly the 3 character Samsung CSC (customer service code) code(s) in your refurbished phone. If the hardware says it is Qualcomm processor, then it probably is a North American hardware version of the S7.

Handy free hardware information tool for Samsung smartphones:

I use a free hardware information tool called "Phone Info *Samsung*" written by vndnguyen which is available on the Google Play store. It shows not only the phone model number, but the CSC codes, the date of manufacture, hardware, and all available sensor data. You might want to install it and see what that app finds. It has a few ads, but they are unobtrusive. Hint: disable notifications for it if you don't want to get "tips" from the author.

Discussion of hardware in North American models:

Note that the hardware for all the North American models is identical (with the exception of one Canadian carrier that uses the European/Asian version of the phone), and they all have the same Qualcomm processors and chipsets. All that differentiates them is the firmware and CSC code that is flashed onto them. The NA motherboards all have "SM-G930V/P/R4/A/T" printed on them. The cellular radios on the NA motherboard include the GSM radio bands used in North America and they also include a radio for the CDMA bands used in North America. IIRC, the GSM bands cover most but not all of the European/Asian GSM radio spectrum, so the phones should work outside North America, but possibly won't get quite as good reception as the European motherboard would get. One last comment about the NA version of the phone: If the phone has been carrier unlocked, it is possible to flash any of the various NA S7 carrier's firmware or the factory unlocked G930U firmware onto it. I have personally tested this. Flashing the G930U firmware onto a NA phone is a great way to get rid of all the carrier-installed "bloatware" apps, leaving only the Samsung interface and apps and the Android apps. However, flashing different firmware onto a phone does NOT carrier unlock the phone -- I found that out by trying it (the phone booted up, but when a non-original-carrier SIM was installed, it asked for and required a SIM carrier unlock code).

Discussion of hardware in European/Asian models:

The European/Asian version of the hardware is, as you mentioned, different than the North American version, and uses a Samsung manufactured Exynos processor and related chipset, and other hardware is different as well -- including the antennas, loudspeaker, and charging daughterboard. Interestingly, the European/Asian motherboards have "SM-G930FD SM-G930F/W8" printed on them, possibly indicating that the difference between the G930F and G930FD motherboards is, similarly to the NA motherboards, only the firmware and CSC code -- the actual hardware may be the same (other than the G930FD SIM tray which is capable of holding a 2nd SIM card OR a Micro-SD card). My understanding is that the European/Asian models do NOT have the capability to connect to CDMA networks -- and only will work on GSM networks. Again, IIRC, the GSM radio spectrum is slightly different in Europe/Asia and North America. However, I do know that the G930F and G930FD models will work in North America on the GSM networks, again, possibly with some reduced reception due to band differences. I have personally tested this by putting a US T-Mobile SIM into a G930FD phone I repaired and it worked well.

I have 3 questions for you folks in Europe or Asia that repair the G930F/G930FD phones:

1. Would you please clarify whether or not the motherboards for the SM-G930F and SM-G930FD are actually identical and only the firmware and CSC codes (and SIM tray) differentiate the two?

2. If a European/Asian phone has been carrier unlocked, can a different version of the European/Asian firmware be flashed onto it?

3. Are there factory unlocked versions of the firmware that have no carrier "bloatware" apps for the SM-G930F and SM-G930FD? If there are, please identify what they are, and supply links where to find them. I am not talking about custom builds -- but rather genuine Samsung firmware that is not carrier specific.

I hope this helps to clarify things a bit.

Philip