Groupon and Living Social have differences in their discussion board, opt-in subscriber base, payment structure, and review restrictions. Groupon has a discussion board where users can engage in conversations and share their experiences, while Living Social may not have this feature. Groupon also has an opt-in subscriber base, meaning users have to actively subscribe to receive their offers, while Living Social may have a different approach. The payment structure may differ between the two platforms, with Groupon possibly having a different system for merchants to receive payments. Lastly, Groupon may have review restrictions in place, whereas Living Social may not have any restrictions on user reviews.