Ok, it really is basic comprehension of inclusion.
Watch this first
https://youtu.be/5_oCRtEN2pIThen consider the set of the following elements:
Diodes (has its own name and symbol)
Zener diodes (has its own name and symbol)
Tunnel diodes (has its own name and symbol)
Metal Oxide Varistor (has its own name and symbol)
Neon NE2 lamp (has its own name and symbol)
Incandescent lamp (has its own name and symbol)
This is a set of...
of...
...nonlinear resistors!
Yeahhhhh!
Now take this big huge set of nonlinear resistors, and put it near the set of linear resistors (they also have their own symbol).
What have you got now? What is the set formed by the set of linear and nonlinear resistors?
It's a set of...
...
Resistors!
Yeahhhh!
Since linear resistors are so to speak the default, we give them the short name of resistors (after all they have been introduced with this name in high school). I hope this won't confuse you.
But apparently it does. Big time.
We call ordinary cars just "cars" even if the set of cars includes formula1 race cars. So, in the same vein the set of cars contains the cars you can drive on public road (which are called just "cars") and the F1 racing cars, which you can't drive on public roads. The F1 cars have their own name, their own circuit, their own regulations but are still part of the greater set "cars", but are disjoint from the set of public road homologated cars (or "cars" in short).