I don't think they are all the same.
To me the best seeds are saved seeds if you were happy with the crop. Over time this can give you a "landrace" strain that is especially adapted/suited to your specific climate and land. Most important thing if saving seeds is to always save seeds from your best plants, not the last ones to mature.
They say not to save seeds from hybrids but some sold as hybrids may not be. I've had good luck with tomato seeds saved from hybrids.
We'll see, we have a mixture of both.