Thanks for the reply. the image you had attached is for Arduino UNO.
Can you please share the difference for Arduino Mega 2560 and Arduino Mega 2560 R3?
I think the differences are the same - separate pair of pins for I2C and the ioref and unused pins on that other header - if a non-R3-like Mega2560 ever existed; unfortunately the official documentation doesn't mention the "R3" for the Uno or Mega2560!
Note also that markings and names of items in listings for clones of the Arduino boards are not always consistent - just look for whether it has those extra pins if you're working with a shield that uses them.
It is not relevant for that TFT shield, though - as you can see in the picture of the underside of the board, there are no pins installed to plug into those "new" pins on the R3-style boards. So it doesn't matter if the board you plug it into has them.
❝ The Mega2560 differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the ATmega16U2 (ATmega8U2 in the revision 1 and revision 2 boards) programmed as a USB-to-serial converter.
Revision 2 of the Mega2560 board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
Revision 3 of the board has the following new features:
• 1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
• Stronger RESET circuit.
• Atmega 16U2 replace the 8U2. ❞