The main difference between Bitts and Bollard is that the Bitts is a deck-fitting on a ship or boat, and used to secure ropes and Bollard is a short, vertical post used in mooring, traffic, etc
Bitts are paired vertical wooden or metal posts mounted either aboard a ship or on a wharf, pier or quay. The posts are used to secure mooring lines, ropes, hawsers, or cables. Bitts aboard wooden sailing ships (sometime called cable-bitts) were large vertical timbers mortised into the keel and used as the anchor cable attachment point. Bitts are carefully manufactured and maintained to avoid any sharp edges which might chafe and weaken the mooring lines.
A bollard is a sturdy, short, vertical post. The term originally referred to a post on a ship or quay used principally for mooring boats, but is now also used to refer to posts installed to control road traffic and posts designed to prevent ram-raiding and vehicle-ramming attacks.
A rides to anchor
A strong vertical post of timber or iron, fixed to the ground and/or on the deck of a ship, to which the ship’s mooring lines etc are secured.
A similar post preventing vehicle access to a pedestrian area, to delineate traffic lanes, or used for security purposes.