Supplied Diameter also referred to often as minimum supplied diameter is the minimum inner diameter of the heat shrink as supplied by the manufacturer. This means that if you order a 1/4" supplied diameter the minimum supplied inner diameter of that heat shrink will be 1/4". It also means it may vary slight over that 1/4" minimum.
Recovered Diameter or maximum recovered diameter is the maximum inner diameter that the heat shrink will shrink down to. Even if the heat shrink mentioned above was slightly over the 1/4" supplied diameter it would shrink to at least the maximum recovered inner diameter specification when heated.
See also How to measure Heatshrink tubing diameter.