Good question. My sister was born a whole lot angrier than I was. We had much of the same childhood, but she was naturally more high-strung than I. It can be learned, too, I'm sure. Yeah, Ariann is in her second year of formal studies. Her Hebrew sounds pretty good and we talked about the recent history of Judaism over dinner one night. She's getting married in early October to a hilarious, really sweet lawyer. I forget what kind of lawyer he is, but it's one of the less evil ones I approve.

A derivational suffix is one that changes the form class of a word - that is, it changes a word from one part of speech to another. If "able" is your root word, an adjective, "ity" would be a derivational suffix changing it into the noun "ability." Inflectional suffixes, on the other hand, don't change the part of speech. They're used within a part of speech, often to identify it as such. The verb "starve" can get an inflectional suffix "s" to agree with a different subject.
Sure, the concepts are all easy and kind of useless. There is a small subset of life in which having the language to talk about language is useful. Very small.