The LQS or Listing Quality Score is an in-house algorithm that we use to measure the quality of a listing and it goes from 1 to 10 with 10 being the best possible score. It takes into account the length and keyword richness of a listing's title, its bullet points, description, as well as the number and resolution of the photos on the listing.
The LQS is an optional filter you can use in Extension and in Jungle Scout's Product Database to find products with listings you can potentially improve upon (you can also see an average LQS in the Product Tracker and the Rank Tracker).
On the other hand, the LOS or Listing Optimization Score is a feature of the Listing Builder tool. This rating lets you analyze your listing and find opportunities for increasing your rank on Amazon.
You can learn more about each option here: