Small pipes used to specifically refer to a design of bagpipe that had 1 common drone stock holding the drones. The drones lay across your chest and traditionally are bellows driven. Typically you would play these sitting down. They are made to play indoors and are very quiet when compared to the Great Highland Bagpipe.
Today, they are still referred to in that manner by some makers and can also generically be referred to any design of a quiet indoor pipe of any design.
The Folk pipe is a McCallum specific product that is essentially is a miniature bagpipe with 3 separate drones and is lung driven…made to be played indoors.
The Fire Side pipes is a Gibson specific product that is also essentially is a miniature bagpipe with 3 separate drones and is lung driven…made to be played indoors.