Pin and pad differences in Altera FPGA chips

In Chip Planner, when you watch your feet, you'll see the pin and pad appear at the same time,

such as pin120/pad174 Bank 4

So what's the difference?

Pin refers to the chip is packaged in the pin, that is, the user sees the pin;

Pad is the pin of the wafer, is encapsulated in the inside of the chip, the user can not see.

There is also a wire connection between the pad and the pin.

Pad also refers to the input and output buffer/register unit.

Further in the Resource property Editor see the PAD as follows

When this PIN is input, the signal flows from Pin-pad-padout-input buffer

When this PIN is output, the signal flows from output buffer-padin-pad-pin

Pin and pad differences in Altera FPGA chips