How is Pam's Song and Shielding Scroll different?

For all purposes i believe a shielding scroll its basically a white scroll you can buy with nx?

seeing how WS at scania FM is about 140m-150m (with the NX rate of 1:50m) its much cheaper to go with the Shield scroll bundles (11 of them)
that is of course until they remove the discount
Most merchants are noticing this and started selling WS at 80m
if you are lucky enough its still going on now at FM