You are confusing the terms.. they are the same...
Post# of 1782
Also from white paper...
"US FDA 510(k): a regulatory background
If you want to introduce your medical device to the US market, you need to obtain clearance from the FDA. This clearance is obtained from the FDA via a 510(k) submission, also known as Pre-Market Notification. Nearly all Class II (medium-risk) devices, as well as a small number of Class I (low-risk) and a few Class III (high-risk) devices, must go through the 510(k) process. Most Class III devices obtain market approval via the Pre-Market Approval (PMA) process, which is significantly more strenuous than the 510(k).
The 510(k) process has evolved and the requirements are more stringent: the FDA implemented a Refuse-to-Accept policy, the eCopy policy, and issued many guidance documents. In this white paper, we will discuss recent updates to the FDA’s expectations for the 510(k) submission and an overview of the preparation and submission process."