What is the differance between Installation Art , "other conceptual art" and sculpture?

Installation is somehow big. If you can't carry it away it's an Installation.

If it's small enough that you can carry it away and when it's technically not unique (so you can't recognize a signature by the making, or - even - somobody else did it, like the "overpainted Sebastian Bieniek") but - may be - by the "spin" of the idea, than it's  Bieniek's "other conceptual art".

And than: sculpture is when it's made by the artist himself and one needs a little "artist like" skills to do it, or at least everbody would do it kind of different, but this "different" was made by the artist himself.

Nevertheless some artwork like "Recycled Sol LeWitt" , or the "The Stolen 100 DM" are still hard to collate. What is it? At the beginning it's "Action Art", than depending on the presentation, it could be an Installation (if you take a lot and make it big), and if you just take (one) the final result could also be a sculpture, but according to the definition "without special skills and skill-signature it's other conceptual art, it's "other conceptual art.

(Bieniek's definition)

A spontaneously sent sculpture made of wooden strips that should actually be made into canvases. Wood sculpture. Dimensions: 200cm x 160cm x 50cm, wood.

Due to lack of space, the work could not be taken with you when moving to Berlin and was therefore destroyed.

"Framed Star" (ger. "Rahmenstern") by Sebastian Bieniek, 1997.

Check also "Barrier Tape Art" by Sebastian Bieniek (2020)