The only main difference is that of the Coating which in case of marshmallow frosting sheets is MADE WITH REAL MARSHMALLOW! They are more flexible and durable than most frosting sheets. They are slightly different from the premiums but results are almost same in terms of quality and other difference is that our premium plus is A4 in size which is a bit narrow - (8.25" x 11.75") and on the other hand the marshmallow sheets are 8.5" x 11"
You can prefer to use the marshmallows sheets if you think you need them to use only for marshmallows or can simply use the premium plus sheets for all edible printing purpose.