The Americans tend to give more than Europeans (2.1% of GDP versus less than 1% for the EU). A (not so recent) article in Forbes gives an interesting taxonomy of the some of the reasons motivating donation.
The more religious the country the more you give to churches or equivalent which in turn give to those in need. In 2017, religious groups were the largest beneficiaries in the US, grasping 31% of the total $410bn donated.
Lower income disparity and lower poverty causes a lower rate of giving, as the needs are less perceivable to givers;
Europeans give less since they are highly taxed and tend to assume that it's the government's responsibility, not their own, to take care of the poor. It is obviously also correlated to how much money you bring home after tax;
More cynical, wealthy Americans give to build a monument for themselves as the love to be remembered.
We picked some, and there are of course others, but this is good food for thoughts.