Generally we use both terms Magnetic intensity and magnetic field interchangeably but there is a distinction between them.
Magnetic intensity shows how much intense a magnetic field is. It can be expressed in two ways
First is magnetic field second is magnetic flux.
To analyse Magnetic Field, you can consider it as magnetic field lines across a magnet which goes from north to south. Whereas magnetic flux can be visualized as magnetic field lines passing from unit area.
Magnetic field is denoted by B and its SI unit is Tesla.