Here’s another scenario for the latter case that gave me headaches.
I have a series of products that each have a set of features. Say printers.
Printer 1 has inkjet, WiFi, 2-sided, network printing and color as key features.
Printer 2 has inkjet, 2-sided and color as key features.
Printer 3 has laser, WiFi, network printing as key features.
The user inputs the features they want. Say WiFi, 2-sided and color. In one case you might want to show all printers that have ALL those options, in another case you might want to show printers that have ANY of those options.