The clear one contain Benzalkonium chloride, it's commonly use in antiseptic and spermicide. It has high pH that can retarded the corrosion in metals.
The blue one contain Copper sulfate pentahydrate. It can be found in swimming pool algaecide and aquarium parasite killer. It is deadly poison at concentrate stage.
Both serves as biocider but the white is better choice if your loop has a lot of mix metals.