b5f7529a_apbooking___Creating_Keepsakes__Blending_Mode
[Effect] Selects the color from the base image and the blend image, and subtracts one color from the other, depending on which has the greater brightness value. [Blending Mode] 
Difference
Blending Modes Cheat Sheet | The Best of Digital Scrapbooking | Creating Keepsakes
Blending Mode