Just eyeballing the charts without any jitter, it kinda looks like Effective Altruists more often report precise donation quantities, while non-EAs round things off in standard ways, producing dramatic orange lines perpendicular to the Y axis and more of a cloud for the blues. Not sure what to make of this, even if true.
Possibly EAs think about their donating more and are thus more likely to be able to look up the exact sums they've donated. While non-EAs might be more likely to just donate to some random thing that seems like a nice enough cause, and then forget the details.
http://www.gwern.net/EA%20donations