The key difference is the dosage level per spray, the different colours are not related to flavours.
DLuxInfant delivers 400IU (10µg) per spray and is flavour free.
DLuxJunior delivers 400IU (10µg) per spray and has a natural peppermint flavour.
DLux1000 delivers 1000IU (25µg) per spray and has a natural peppermint flavour.
DLux1000 Vegan delivers 1000IU (25µg) per spray and is flavour free.
DLux3000 delivers 3000IU (75µg) per spray and has a natural peppermint flavour.