The packages are grouped by who does what, not by how much you are willing to spend. The difference between the first group and the last is whether Covorn makes the material, posts it for you, or runs the advertising behind it as well.
Within a group, the three sizes differ in volume — more flyers, more carousels, video added. A bigger package is not a better version of the same work; it is more of it.
Where a package involves advertising, the fee is for running the campaigns. What you spend with the platforms is yours, paid by you, and never part of what Covorn charges.