The difference between drug use and drug abuse is that drug use is infrequent and drug abuse is constant.
Basically, the difference between use and abuse is degree. Any drug use can turn into abuse if the user becomes dependent. Drug dependency means that the person cannot live without the drug. This is when a person is said to be abusing the drug. Some drugs are very addictive, and drug use quickly turns into drug abuse. However, even just using a drug can be dangerous. One does not have to abuse a drug to have serious health consequences.
Drug use is different because people use it when they're sick or in need of drugs or if it is the case of bad drugs such as meth then that is a different story. But if a person abuses drugs they use it way too often and way too much and get an overdose
Drug use is not as frequent as drug abuse. When a person abuses drugs they use it too often, and too much.