What's the difference between pontoon and spontoon?

Pontoon

Definition:

(n.) A wooden flat-bottomed boat, a metallic cylinder, or a frame covered with canvas, India rubber, etc., forming a portable float, used in building bridges quickly for the passage of troops.
(n.) A low, flat vessel, resembling a barge, furnished with cranes, capstans, and other machinery, used in careening ships, raising weights, drawing piles, etc., chiefly in the Mediterranean; a lighter.

Example Sentences:

(1) There are kayaks and paddleboards to rent and a pontoon to swim out to.
(2) Most of the work will be carried out from the banks because it is safer, but workers also hope to use an amphibious dredger and could operate from pontoons in the river.
(3) There were no major complications with the pontoon method, which is now a standard treatment for femoral fractures in children.
(4) A method of spica cast treatment that immobilizes the limb in the 90-90 position using a reinforced cast incorporating a distal femoral traction pin--the pontoon spica--allows for early cast application and discharge from the hospital and encourages early motion of the knee joint.
(5) Underneath an awning on the pontoon, a gigantic banner proclaims "Venezuela", a gift from the young musicians of the Simón Bolívar Orchestra.
(6) Efforts could then be made to refloat it using specialist inflatable pontoon equipment that was being sent to the scene and could help direct it back towards the sea.
(7) Many of the refugees had crossed the pontoon bridge at Peshkhabour over the Tigris river.
(8) The origin is discussed: it is assumed that the corpse changed its position only minimally in the half-year period after immersion and did not drift with the stream, but on the contrary had stuck fast on or under a pontoon and was rubbed and ground against a pole or something similar.
(9) • Look out for the white wooden pontoon on Hornstulls strand adult £5, child 4-19 £1.70 And don’t miss … Launched as an alternative to mainstream tourist guides, Underverk is a platform and initiator of convivial art and design events taking place in Stockholm.
(10) (The walking tours visit the old pier and pontoons, the Brae with its crofts and ancient trees, the Open Air Church and the War Memorial.)
(11) Encircling the island are the dredgers and the suction ships and the thousands of illegal pontoons sucking up ore from the seabed like mechanised mosquitoes.
(12) The pontoon method provided better results in control of alignment than the conventional method, with no greater discrepancy in leg lengths than generally observed after skin traction and hip spica casts.
(13) From the hotel there are pontoon boat trips across the lake, canoes to rent and hiking trails to the Grinnell glacier.
(14) A short walk down the beach, a group of seabed miners are milling in front of their pontoons.
(15) He has therefore thrown himself behind the London River Park , a privately financed plan for a series of pontoons floating in the Thames that, while they will have some benches and green stuff here and there, will also have extensive corporate hospitality areas to pay for the project.
(16) "The producer cited 'safety' grounds, because I might slip on a pontoon.
(17) As the manager of 20 pontoons – makeshift rafts assembled from wood, thatch, plastic barrels and suction hoses – he is nervous.
(18) When you play the card game pontoon, you have the option to "stick" – keep the hand you are holding – or "twist" – draw another card.