LiF is almost insoluble in water where as LiCl is soluble not only in water but also in acetone. This is because of

LiF is almost insoluble in water due to its high lattice energy but LiCl is soluble in water due to high hydration energy of  Li+ ions. LiCl is also soluble in acetone due to its predominantly Covalent nature (because covalent character increases with increase in the size of anion )