Refund means that the possibility of getting the money is 100% but in case of chargeback , the possibility may not be the same, rather it will be less only.
I would like to support the views of marigot in this. both terms have got lots of difference. In refund, where the sellers refund the money to the buyers if they have returned the product without any flaw. In case of chargeback, it tells what he has to pay on a situation where the seller or manufacuterer has tried to deceive the consumer . It is unethical.
Most of them over here have already clearly detailed manner differentiating the both. In fact, refund means giving back the complete amount to the consumer incase, the product is bad or faulty. But, chargeback is completely different from this.