LEGO Legends is a term used by LEGO for rereleased sets, usually brought back because of perceived popularity among fans.
Many early sets in the line were packaged using grey boxes with black and white photos.
The sets were generally faithful reproductions but occasionally stickers replace printed parts, or newer parts are substituted for older ones. For example U.S.S. Constellation (398), when rereleased as 10021, used washing machine bricks instead of the (long out of production) 1x1 windows of the original set.
Set numbers are often 5 digit of the pattern 10xxx, but other LEGO Direct sets such as UCS sets often also use that number pattern, so the number itself is not a definitive discriminator.
- set list from Peeron
- set list from the LUGNET Guide