Fabric content is unknown, but I would guess it is a polyester taffeta for the dress, and a polyester chiffon for the topper.
Dress is sleeveless with a scoop neck and center back lapped plastic zipper.
Topper has long sleeves, crew neck, and trumpet sleeve.
Finally, it has a hook and loop closure at the neck.
This just screams Mother of The Bride/Groom to me…