Well, it's a start.
Polenta is ground corn. Semolina comes from durum flour. Semolina and polenta can be prepared similarly; both can be cooked down with liquids into a polenta-like mush.
At sonsie, the sous chefs always made polenta with semolina flour. And I'm pretty sure it was only semolina flour they used.
It doesn't surprise me that my school textbook has no entry in the index for either semolina or polenta. Poliane, Fernand Point, poly-whatever compounds. The learning curve continues, but now it really is time for bed, and some Rodney Strong wine I scored from the function last night. And well-needed sleep.