Approaches, methods, and techniques are separate parts that, in the end, come together to accomplish a common goal. They are interdependent components of a whole intervention.
An approach is the philosophical part of the intervention. It is described by Edwards (1963) as a sum of correlated assumptions. By assumptions we mean theoretical and baseline foundations. For example, The Functional Notional Approach is based on a speech theory that places words (utterances) within specific contexts. The fact that it is based on theory is what turns it into an "approach".
A method is the plan of action that you put together based on the approach that you are going to follow. For example, the teacher will put together a list of techniques and that will be the process of intervention that will be performed. Another word for method is procedure, or it could be also known as an arrangement to be followed.
A technique is an "explicit procedure" used to carry out the method. Techniques imply proficiency and skill, for which it is necessary to be content-knowledgeable as well as task-knowledgeable to apply techniques that can be measurable with data results.
In other words, techniques enable the method while the method has to follow the approach. Not all has to be hierarchical but interventions do seem to follow this trend.