That can't becouldn't have been a Raspberry Pi 3 Model B+... because that model doesn't existdidn't exist!
TheUntil March 2018, the only Pi to have a Model B+ version is the original Raspberry Pi 1 Model B+. The differences between the Pi 1 Model B and B+ are as follows:
- Tidier layout
- 40 General Purpose Input/Output Pins (GPIO) compared to 26 on the Pi B
- Improved connectivity (4 USB Ports compared to 1)
- Improved audio quality
- Lower power consumption. Switching power regulators reduce the power consumption to between 0.5 W and 1 W
- Push-push microSD card slot
Regardless, since your Pi specifically says 'Raspberry Pi 3 Model B V1.2', you can be absolutely sure it is, as stated, a Pi 3 Model B.
In fact, the Model B iswas the only model of Pi 3 available as of late 2017—the Pi 3 Model A hasn'thadn't yet been released. So, as of now, you can be sure that if it's a Pi 3, it's a Model B.
You might also like this identification guide if you're in any doubt as to what type of Pi you have.