ETA: In trying to answer the OP, that overlap shows that this isn't a sufficient point to distinguish between the two. (Remember, the OP wanted a quick and concise way of describing the differences. If your purported "difference" isn't actually different, it doesn't distinguish the two.
I said that there is overlap in ethics, but that science does not give us our guiding values, it just helps us decide how to act in most accordance with them.
I don't think religion can "give us our values, our basic guiding principles" either. I think we evolved with a moral capacity (the same way we evolved a capacity for language), and the specific norms we learn are socialized by our upbringing--which need not have anything to do with religion.
Yes, I agree that a person does not necessarily need to get their values from religion, but that is one of the major points of religion, which is different from science.
Also, as pointed out, the track record of religion for inculcating guiding principles has been spotty at best.
I think this might be what Darat was trying to get at, but just a sentence is impossible to debate. Elaborate please.
I stand by my earlier example. We can all agree that we don't like unwanted teenage pregnancy and STDs. As an educational goal, we'd like to teach kids how to avoid these things. Conventional sex ed arms them with the correct and best information. Abstinence only sex ed does not. Approaching the problem scientifically, we can test the outcomes of these programs. Religion, in this case, motivates a choice by a bogus moral dictum (not part of our basic guiding principles or underlying beliefs of right and wrong), and will cling to abstinence only programs (because, according to them teenage/premarital sex is "wrong") regardless of or in spite of the evidence at hand. So which is a better moral guide in choosing the nature of sex ed?
I find your analysis interesting because you seem to be assuming that there are universal principles that are correct and religious principles are tacked on and "bogus".
I really like this discussion. I have class now, but I will be sure to come back tonight

. I have more to say about this example, but I don't have the time. I'll just try to breeze through the rest:
Also, we're learning more about the brain and human behavior all the time. I suspect the questions that you say are in the bailiwick of religion only might someday be answered by science. (There was a time, no doubt, when other questions were deemed untouchable by science--human origins, for one.)
I don't think values are only for religion, but I don't think they can be "answered" by science.
Sure, we may have evolved the capacity for morals, but we still have to choose among many different values like "Might makes right", "All life in infinitely valuable", "Those who take life deserve to have their life taken", etc. I really see how science can enter a field where you can't empirically test anything.
Finally, you're making the mistake that Skeptigirl rightly criticized: you seem to be saying that without religion there would be no values or basic guiding principles for living life. I, and plenty of other atheists and non-religionists do not live lives devoid of values. (For example, I'm a vegetarian and a pacifist--both based on moral convictions and having NOTHING to do with any religion or religious beliefs. I also have plenty of other purely secular values shared by most people--relating to family, duty, etc.)
I'm not. I'm saying that those things are one of the major points of relgion, while the major point of science is to make models as accurate as possible to physical reality.