What's the different between Imaje printer Modulation Assembly 9450 white color and red color

ENM51312 Modulation and ENM40038 9450 Modulation are both the print nozzle of Markem -Imaje printer 9450.Both of them are for G nozzle .But there are some different.
ENM51312 Modulation body GC Assembly 9450 is color red.The red color nozzle assembly is for normal black ink such as MB177.