Private label
With private label resell rights, purchasers may not only resell the product but may also edit the content or product and claim it as original work (in effect, becoming its author).
With PLR you can modify the content in any way,
In short:
you can claim authorship,
you can sell it with the rights you choose (examples: resell rights, master resell rights),
you cannot claim copyright on the original product.
Master resell rights
Master resell rights or master resale rights include permission to pass on resell rights along with the product to customers.
In short:
cannot be modified,
cannot claim authorship or copyright,
can be resold to end users,
you keep the profits from reselling.