Today, we saw the release of a new comedic video, "Rainn Wilson lures Blake Griffin into his Van", where Rainn Wilson interviews Blake Griffin.

Blake says: "I had a meniscectomy, which is, uh, they took out part of my meniscus."

In an article on Clipperblog, Andrew Han explains the difference.

...his recent knee procedure was a partial meniscectomy and not a meniscus repair (Partial meniscectomy is an assumption I’m drawing as opposed to a full meniscectomy because Blake expounds on the procedure, "they took out part of my meniscus"). This is a similar procedure to the one Blake had on his right knee his freshman year of college. A partial meniscectomy generally has a faster recovery time than meniscus repair (Griffin played in a college game two weeks after his right knee meniscectomy).

From what I gather, a meniscectomy means that they took out part of the meniscus. A meniscus repair is actually fixing the meniscus. So this means that Blake is now missing partial meniscus in each knee from meniscectomies.