Active listings are listings that are found on the Manage Listings page of LM. LM is in full control of active listings, meaning it is syncing out QTY and listing data (non-Amazon) to it. It also allows LM to use the active listing as a base for creating listings on other marketplaces.
Inactive listings are found on the specific listing page for the channel they exist on, with a little plug icon above the thumbnail image. LM does NOT control QTY or listing data for these listings. Nor will you be able to use them to create other listings.