A piano accordion is an accordion equipped with a right-hand keyboard similar to a piano or organ.
In comparison to a piano keyboard, the keys are more rounded, smaller, and lighter to the touch. These go vertically down the side, pointing inward, toward the bellows, making them accessible to only one hand while handling the accordion.
The bass piano accordion is a variation of a piano accordion without bass buttons and with the piano keyboard in an octave lower. They typically have around 3 octaves.