These are two important words to mull over. Generosity is often thought of in terms of money, although it is also sometimes associated with the giving of time. In terms of money, big philanthropists like Bill Gates and Warren Buffet easily comes to mind as having given away huge amounts of money, both in dollar terms and in the percentage of their wealth. Who can fault them?
It is interesting therefore to note that the bible says: "If I give all I possess to the poor and surrender my body to the flames, but have not love, I gain nothing (1 Cor 13:3)". This is what charity means. Charity comes from the Latin word "caritas", which means altruistic love. Charity is benevolence towards others less fortunate than ourselves. It is an attitude of kindness and understanding towards others. On the other hand, generosity is a subset of this feeling of charity and altruistic love. One can be so generous as to give all he possesses to the poor and surrender his body to the flames, but if he has not love, he has gained nothing.
By all means, be generous. Only do it with love, with an attitude of kindness and understanding towards others. Be charitable, not just generous.