What's The Difference Beetwen This 2 Nizorals?

[Besart]

Hello,

I wanted to buy nizoral shampoo but I see there are like 2 kind of them.
One blue one red. Red is cheaper.
Which one to buy? What is the difference?

 

[Zoro]

blue one is non prescription 1% ketoconazole, red one is prescription strength 2%.