I would have said notepads and notebooks mean the same thing but the first wasn't accepted.
Report it. Also, note that "тетрадь" refers only to notebooks/notepads that open at the side and are used primarily for making notes and doing tasks while learning.
Does 'наши' have different forms/spellings based on the gender of the noun it is modifying, or does it always stay the same?
Would be copybook an equivalent UK english word? At school, we used to call it so (I guess, I am italian)
I'm not sure about equivalency...
Тетрадь generally means a thin book of blank lined pages for writing notes. So it, first of all, definitely is a notebook. A tenth entry in a dictionary may say though that тетрадь can in rare instances mean any thin book whatsoever.
A copybook is largely associated with a student's exercise book containing samples of good handwriting to be copied. That would be тетрадь for as long as it is some folded paper, but more specifically it would be пропись.
I have a question, is this word "тетради" refer to the notebook gadgets (small laptop) or just in the context of the literal books we use to take notes?