can anyone tell me the difference plz
Magnetic flux density is another name for the magnetic induction, $\displaystyle \vec{B}$. This is also (incorrectly) known as the magnetic field.
A "visual" conception of the magnetic flux is a measure of the number of magnetic field lines passing through a fixed area. A more precise definition would be $\displaystyle \Phi _M = \int \vec{B} \cdot d \vec{A}$, where the integral is over a (usually, but not necessarily, closed) surface.
-Dan