It's blood. I think that some of it has to do with the thickness of the body they are cutting through. Maul's torso/waist it pretty sizable when compared to Anakin's arm in AOTC, Dooku's wrists and head in ROTS, Mace's wrist in ROTS and Luke's wrist in ESB so Maul's "flesh wound" wouldn't cauterize nearly as quickly.
The wild card obviously is Ponda Baba, but maybe Aqualish are more vascular than humans so they're "bleeders" in comparison.
Also IIRC, the Wampa in the ESB SE had a fair about of blood loss after Luke's handiwork as well.