Difference between a methodology, a method and a workflow?

Of course the three words refer to the same concept (an established procedure for accomplishing or approaching something), but they range from a more abstract or general point of view to a more pratical and detailed plan.

The methodology is the set of methods and approaches. E.g., the methodology to develop new medication is to conduct pre-clinical research and clinical trials.

The method is a particular methodology employed. E.g., administer the drug to mice and study their response in particular ways (monitor their inflammatory response, behavioural changes, etc).

The workflow is the detailed list of actions performed in order to implement the method, something like the sketch of an algorithm, which would be the next word in the sequence.

I must admit I don't agree with @Joce's analysis.

A "methodology" is an examination or analysis of a method, or a set of methods - typically to explicitly discuss common principles or constraints, to define a heuristic to devise a method, or to evaluate the relative advantages of different general approaches or alternative methods.

A "method" is way of doing something - which may not be the result of, or consistent with, any explicit "methodology". The methodology may be ad hoc, implicit, unexamined, or traditional - either way, supported by no clear analysis.

A "workflow" is a term of management jargon which is not really any more specific than the word "process", but may imply an ensemble of conceptually discrete processes (or stages within an overall process) which are in some sort of relation, especially if there is a division of labour and a piece of "work" moves between process operators.

At other times, "workflow" is just a synonym for "process", which itself is barely distinguishable from "method". I would only note that "method" tends to connote a certain amount of agency and purposive oversight, whereas "process" implies something that is done without reference to purpose. For example, the natural world may have "physical processes" but not "physical methods", whereas a person may "follow a process" or "use a method" with implications accordingly about how much purpose they have in mind during execution.