The easiest way to discern between splash and sabino, for me is this:
Splash
Edges of pattern make straight geometrical lines
Markings generally not symmetrical when viewing both sides of horse
Face markings tend to be bottom heavy and off centered
Blue eyes present, with pink skin around them
Sabino
Edges of pattern are jagged, frayed, patchy or speckled
May have "penciling" around edges of pattern
Markings tend to be symmetrical both on the body and the face
Face markings tend to be centered on the face, with white found on chin and under jaw
Lips will have dark "mustache" on sides of muzzle
Brown eyes present