The basic form-factor of the Pi 2 Model B is nearly 100% the same as the Pi model B+
- The shape and size of the PCB is the same
- The 4 mounting holes are in the same location and are the same size
- The USB, Ethernet, A/V, HDMI, micro SD and microUSB connectors are int the same exact locations and are the same size
- The Camera, Display and 40-pin GPIO connectors are in the same exact locations and are the same size
The physical changes include:
- Processor chip is larger, has moved slightly
- The RAM is now soldered onto the bottom of the board (no longer PoP)
- Other components and chips are moved around slightly to make space for the larger processor and RAM chip on bottom
This means that 99% of cases designed for the Raspberry Pi Model B+ will work with the Raspberry Pi 2 Model B. This includes the Adafruit B+ Pi cases
One exception is some Pibow cases which have a layer that has cutouts for the specific location of the processor. Pimoroni has informed us that they will have a new case design that is compatible with both. Check the description of any case to make sure it is compatible with both Raspberry Pi Model B+ and Raspberry Pi 2 Model B
The processor has completely changed on the new RaspberryPi 2, instead of a ARM v6 core chip (arm6l) the BCM2836 has been upgraded to an ARM v7 core which is a much more powerful core
However, your existing Raspberry Pi SD card images may not work because the firmware and kernel must be recompiled/adapted for the new processor.
If you have a Raspberry Pi 2, and you are trying to upgrade your existing SD card, you will need to upgrade your installation. To do that, log into your Pi 1 and at a console or terminal type in sudo apt-get upgrade to perform the upgrade procedure. You'll need your Pi to be on the Internet to do this. Once upgraded, the card will work on both Pi 1 and Pi 2 computers
If you have any pre-compiled binaries that you are downloading, those will need updating too, in order to take advantage of the speed increase. Anything where you have access to source code can be recompiled and ought to work just fine. Supposedly any ARMv6 software is forwards compatible with ARMv7 but we haven't tested it for sure yet
Quad-core ARMv7 processor means higher current draw.
Just having the Pi 2 Model B running idle (no HDMI, graphics, ethernet or wifi just console cable) the Pi 2 draws 200mA
With WiFi running, that adds another 170mA
If you have Ethernet instead, that adds about 40mA
When doing the heaviest computational tasks, we added about 200-250mA more current. So if you're really using your Pi 2 and you have a WiFi dongle, expect to need 650mA @ 5V, at least. More if you have stuff connected to the GPIO connector, other USB devices, Ethernet as well, etc!
If you're still running with a cheap 5V 700mA power supply, we really recommend upgrading to a 5V @ 2000mA!