Why does oil based paint require thinner to clean up?
Oil based paint is not water soluble and so needs paint thinner to clean the brushes etc.
Beside the chemisty involved, probably the most important difference to you is that oil based paints require a solvent such as mineral spirits (paint thinner) for clean up while acrylic paints only require water. Generally, an acrylic or latex water based paint is going to be easier for you to work with.
We used to clean our sprayers with either mineral spirits or water depending on what type of material we were using, and then leave clean spirits in it under a little pressure to keep anything from drying inside. Today much less oil based paint is used and a water based solution is recommended to keep in the machine to maintain it. If you use oil (alkyd) based paint you should still flush with thinner first…
The technical difference is that oil-based paint has a non-water-soluble "base" to it, and water-based (latex) paints have a water-soluble "base" to them. (Latex cleans with water, Oil does not.) The practical differences are pretty severe. Latex paints clean up with water (the most important feature for some), dry faster, don't show brush strokes as clearly, and don't smell remotely as bad as oil paints. Latex paints should always be used for interior surfaces. Oil…
Lacquer thinner evaporates quicker. It is cleaner or leaves less of a film than paint thinner. Lacquer thinner will thin most solvent based paint but paint thinner shouldn't be used to thin Lacquer. Lacquer dries from the surface painted out and enammal dries from the surface of the paint down to the surface painted. Using the wrong thinner affects how the paint dries and may affect the final finish.
Because soap and water are NOT oil based. Oil based means you need to use an oil-based thinner to clean brushes and spills. The materials used in oil-based paints are not soluble in water, even with the added surfactant effect of soaps. (Some paint may come off hands as the soap loosens the dead outer layer of the skin.)