Of course they sell them as the same thing. The difference is pedantic. Lets be brutal. You are repairing an unusable threaded hole with a piece of coiled wire. The result will be quite close to original but will not be a perfect replica of a theoretical thread form. You are then fitting a screw made within commercial limitations or possibly even the worn screw that came out of the repaired hole. Neither will have a perfect thread form either.

In this case all 26tpi threads are interchangeable, be they BSF, BSC or BRASS.

Save your money and use what you have.

Cheers,