What is the difference between a popularity-based and a content-based approach in recommender systems? Popularity-based approaches recommend popular items to all users, while content-based approaches recommend items based on their attributes. Popularity-based approaches recommend items based on the frequency of their occurrence in the transactional dataset, while content-based approaches recommend items based on their relevance to the user's preferences. Popularity-based approaches recommend items based on their similarity to the user's past purchases, while content-based approaches recommend items based on their novelty. Popularity-based approaches recommend items based on the ratings and preferences of similar users, while content-based approaches recommend items based on the similarity of their attributes