В чем разница между performance и functionality ?Пожалуйста, приведите примеры.

They are quite different and have many meanings. I'll talk about what I think you are referring to, please correct me if I'm wrong.

"Performance" usually refers to how well something accomplishes a task. A car could be a high-performance car, and a smart student can be high performing. Likewise, a lazy student can be underperforming and an old car engine can have poor performance.

Functionality refers to the range of things that something can do; when you ask about the functionality of a piece of software, you are asking what kinds of things it is capable of doing. Something that can accomplish a lot of things like a Swiss army knife has a lot of functionality.

In these contexts, "performance" and "functionality" cannot be interchanged. A student cannot have low functionality, as this implies that the student is not physically capable of much. Likewise, something with a lot of functionality can be good (high performance) or bad (poor performance).