Not a "Bride's Maid" but asked to be in the Wedding Party?

The person that I mistakenly thought was my 'best friend' is getting married and has selected her bridal party, which does not include me. I thought I would be asked to be her Maid of Honor, rather I was given a note at her engagement party (the way she asked everyone including her bridesmaids) saying she considered me a very dear friend and she wants me by her side on her special day as part of her "Wedding Party" as a "VIP". So, I am really not sure what this even means?? I would imagine all the roles and responsibilities in preparing for the wedding, bridal shower, bachelorette party, etc. will be done by the women she has selected to be her attendants. What exactly does it mean to be in the "Wedding Party" but not a bridesmaid? Is that even possible. I am quite baffled. Any thoughts?