These are some differences between collectivist and individualists as I know the terms, and in broad strokes. Most of us are not strictly one or the other, but we do tend towards one more end than the other.

Collectivists tend to value group membership and teamwork. They work towards the good of the group versus individual achievement. They value cooperation over competition. Many Asian cultures are collectivist, whereas the US is an individualist culture. In individualist cultures or natures, personal achievement and gains are valued over group achievements. An individualist does not tend to overly identify with a group to the point of placing their own needs secondary to group needs or goals. Individualist cultures usually have a much higher potential for personal rewards, achievements, and sucesses for an individual, although sometimes success of one can come at the expense of another. This is more evened out in a collectivist culture.

Hmm, that's about all I can remember from undergrad. I do think it's possible to be altruistic whehter you are a collectivist or an individualist. I suppose it depends, in part, on the underlying reasons for altruism. Personally, I don't think either way to be, individualist or collectivist is better than the other, per se. There are benefits and costs to both. I think it's probably good to have both around.

At any rate, I hope that helps.

gg