Chronos is the quantitative measure of time. Kairos is the qualitative measure.
"Kenneth Burke has defined the relationship between discourse and reality in kairotic terms. In his definition, kairos encompasses the occassion itself, the historical circumstances that brought it about, the oral or written conventions of the form required by occassion, the manner of delivery the audience anticipates, their attitudes to the speaker and the outside world. Burke is like the ancient sophists in that he draws from his own literary tradition his insights on persuasive discourse."
-from http://www.lcc.gatech.edu/gallery/rhetoric/terms/kairos.html
More information can be found here: http://english.ttu.edu/kairos/layers/situation.html
The only reason I know about kairos is this: I was a gigantic Madeleine L'Engle fan as a kid and she deals with chronos and kairos quite often. She defined kairos as 'a time outside time'. For example, when one is reading a really good book and loses track of time in the story, that's kairos, I think. (I'm trying to articulate somthing that's really hard to describe. if I make no sense, I'm sorry.)
Literally, kairos can mean 'an opportune moment or situation'. Rhetoric has it as 'the search for relative truth rather than absolute certainty'.
Another interesting page: http://humanities.byu.edu/rhetoric/ Encompassing Terms/kairos.htm This tied my brain in a knot. I suppose I'm not much of a philosopher.
http://www.geocities.com/Athens/Atlantis/3425/page378.htm Interesting about the chi and rho of chronos. Kairos starts with 'kappa'...fiddle. I had some sort of connection going here between chronos/religion without faith and kairos/pure spirituality, but the rhetorical meanerings I googled through have eaten my brain.
-Hollie