When we say 'blue spray' we mean oxytetracycline, which is an antibiotic and which you can only get from the vet or the animal health section of your local agri merchant.
Battles Foot Rot spray contains cetrimide, which is an antiseptic detergent. Great for cleaning a wound but won't do as much to halt an active infection as an antibiotic.
There are a huge number of purple sprays. Some using essential oils for an antiviral, antifungal antibiotic effect, some are simply antiseptic detergent like the spray you've bought.