So what is the difference between QA and Testing, and what is QualityControl?

Many people still confuse these concepts, which, in general, is not surprising, taking into account that in our country they can often be used to describe the same processes. But from a formal point of view, namely, it interests us, as specialists, and these three concepts have essentially different meanings.

Let’s sort things out:

Testing is quality control.
Quality control is the measurement of product quality.
Quality assurance is the measurement and control of process quality, which is used to create product quality (or a quality product).

We can arrange their ratio in the table:

Thus, based on this knowledge, we can build a hierarchy of quality assurance processes: Testing is part of QC. And QC is part of QA.

In other words, Quality Assurance ensures the correctness and predictability of the process, while Quality Control implies compliance monitoring. Testing, in turn, ensures the collection of statistical data and their inclusion in documents created within the QC process.

If we draw an analogy with the design process, for example, of a bicycle, we get the following picture:

with the help of testing, we can determine whether all the parts and the bike itself work as we expect. Of the right materials, it is made, with the use of the necessary techniques and tools or not. That is, it is implied that the tested object already exists.
The task of QA is to ensure that all stages of designing our bicycle are consistent with certain quality standards, from planning and creating drawings to assembling an already prepared bicycle. That is, the quality of the object is paid attention even before the creation of the object itself.