We use your energy signature above and beyond all else because it is the the only infallible aspect of you. There are many people who do not know their birth date, or the accuracy of their birth date, so we did not design our work to require a birth date. Your corporeal body may change through plastic surgery, tattoos, change to your hair, eye or skin color, or etc. Your energy signature is your divine identifier and therefore is the only concrete and unique aspect of yourself that never changes.
If you ever provide us your birth date, photograph, or personal sigil, we will incorporate them, at your request :) However, it is not necessary.
What is the difference, then? If you are someone who practices magick that is specific to any of these key areas, then you may want your bindings from us to have these aspects incorporated. If you wish to have your birth date, photograph, or personal sigil tied to your binding, please provide us the information in your order, or via our support portal (use the contact icon on the bottom right) - make sure to include your order number.