Answer:
Quackery is defined as a dishonest practice from someone who claims to have knowledge and/or skill in a particular subject or field. This is most common in the medical field.
Fraud, on the other hand, is wrongful (illegal) or dishonest practice with the intent on gaining financial gain.
The difference between the two is that quackery typically only applies to medical practices, whereas fraud can apply to just about anyone who is involved in any sort of deceptive and/or fraudulent practice.