practical techniques qus OCR

separation is when you have an aqueous layer and organic layer and want to run one of them off (purifying an organic liquid). recrystallisation is used in purification of an organic solid, to remove impurities (that may be solid, but dissolve in the solvent). unless you mean filtration? in which case u filter under reduced pressure before recrystallisation to remove soluble impurities from a solid, and sometimes after recrystallisation again to make sure you're left with only the solid.