What is the difference between magnetic and primary inductance?
Are magnetic and primary inductance different each other?

No, they are not different unless you want to take into account leakage inductance (2 to 5%). I think you are not understanding the type of circuit they refer to: -

Page 16 and 17 are referring to a 2 switch−Forward Power supply specification and they use an extra inductor in the output circuit seen as L1 in the above schematic. That will be the 27 uH they refer to: -