What is difference between a substance that is solube in water and one that is insolube in water?

There is no such thing as a soluble precipitate

A precipitate a solid that is formed in a chemical reaction, therefor only a insoluble precipitate can occur, and the soluble would remain as a soluble solution.

The difference between a soluble and insoluble precipitate is that a insoluble precipitate is incapable of dissolving in a liquid, and a solid is formed in the reaction, where as the soluble substance will dissolve in the liquid.