Wheat Flour Vs. wheat gluten
These are two related, but different products.

Gluten is protein that is formed from two pre-cursor proteins, glutanin and gliaden, found in wheat flour in the presence of water and under enzymatic activity.

It forms resilient stretchable networks which give yeast raised bread its structure.

Whole wheat flour is... well... whole wheat berries, ground up.  It is mostly starch, but contains all glutenin, gliaden, and the necessary enzyme to create gluten, which forms naturally when the flour is moistened, if given long enough or kneaded to accelerate the process.  However, even a very "strong" flour (bread flour) will have no more than about 10%-15% percent protein by weight, so it cannot form more than that amount of gluten.

Vital wheat gluten is essentially concentrated, powdered gluten, without the rest of the parts of the wheat berry.

They are not freely interchangeable, as the gluten does not bring the starch, bran, and other components that flour does.   You may, in specific recipes, be able to use just gluten, but not in the general case.  And even if substitution is possible, you would have to determine the correct ratio to achieve the desired outcome.

Using vital wheat gluten in lieu of whole wheat flour, in most applications, will either fail completely (no thickening from starch, as in a gravy), or be dense and rubbery, and practically unpalatable (as in a bread).