An "extension of eligibility waiver" is only needed for athletes who are currently in their 10th semester or 15th quarter of full-time enrollment (the NCAA D2 and D3 version of Division I's "five-year clock"). Also, these are the only athletes who will automatically receive an additional semester beyond their "normal" 10 semester or 15 quarter limit.
Younger athletes, let's say a current sophomore for this example, will just have this treated as a redshirt season and will still have 3 seasons to play within their 10 semester/15 quarter limit.
A "season of competition" waiver is the type that will be provided to ANY Division II or III spring sport athlete due to the cancellation of their season because of COVID-19.