Freezer paper has a wax on one side. It allows you to iron it on and then it peels off. With parchment paper there is no wax and it won't stick to the fabric. The freezer paper can be used multiple times. By using the freezer paper method, there is no stabilizer left in the quilt top.
when I did an signature quilt, I starched very heavy and I didn't need to stabilize the white fabric. My signatures were applied after i had finished the quilt. After the signatures were on, I heat set them. Although, I didn't have to heat set, but a little piece of mind doing so.