Patient vs. subject in clinical research

What is the difference between patients and subjects, in clinical research?

I read this paper abstract:

The terms “patient” and “subject” are often used interchangeably when proposing, conducting, or reporting on research. This error is not just a semantic one but also a conceptual one. Proper use of these terms is essential for all parties involved in the research to understand clearly their roles, expectations, and obligations.

which tends to make me think there might be some differences but the actual article is behind a paywall.

Solution 1:

Here is a useful site of clinical terminology.

A 'patient' is a person receiving medical care, while a 'subject' (or 'participant') is a person being experimented on. Often the two categories overlap, but not necessarily. For example a trial to ensure that a drug has no side-effects may involve giving it to people who are not sick, in which case they are a subject but not a patient. Also if a person is in the control group of a drug trial they are not receiving the drug, and it might be stretching the point to classify them as 'patients'.