Are these economics terms?
Yup.
Cardinal utility is saying utility can be measured absolutely, ordinal says it can be done relatively (difference curve stuff).
That is, if I remember correctly from econ.
Pretty much.
You could guess it from the names cos "cardinal" means 1, 2, 3, 4, 5 etc, whereas "ordinal" means 1st, 2nd, 3rd, 4th, 5th etc.
Ordinal, therefore, sez you can rank the utility of several different things, but not put an actual value on them. So you can say, "I prefer Mars bars to Twix", but not "I like Mars bars 2.4 times more than I like Twix".
Cardinal, OTOH, sez that you can say that, although a "cardinalist" would offer a less ridiculous example, e.g. "I'd rather have 50p than a Twix, but I'd rather have a Twix than 51p, therefore a Twix is worth 50p". We make these decisions all the time, even if we don't know it.
LighFang's up!