Both kinds say something about a subject, but the manner of attribution differs.
Direct: “Amr is a physician” — physician is predicated directly of Amr.
Derivative: “Zayd is in the house” — location is expressed with fī.
Derivative: “The property belongs to Zayd” — possession is expressed by lām.
The presence of the English verb “is” or Urdu “ہے” does not settle the classification; one must inspect the predicative relation.