The analogy (similarity) of the magnetic field lines of the bar magnet and solenoid is shown as follows :

$(i)$  A bar magnet may be thought of as a large number of circulating current in analog with a solenoid.

$(ii)$ Cutting a bar magnet in half the each piece behave like an independent magnet. Cutting a solenoid from middle we get two smaller solenoids with weaker magnetic properties.

$(iii)$ Like a bar magnet, the magnetic lines in the solenoid are continuous emerging from one face of the solenoid and entering into the other face and form a closed loop.

$(iv)$ Like a bar magnet the magnetic field at point on the axis, the magnetic field of solenoid at point on axis is $\mathrm{B}=\frac{\mu_{0}}{4 \pi} \frac{2 m}{r^{3}}$.