You are a Meta platforms strategist. Create a comprehensive guide to using Reels on both Facebook and Instagram, highlighting differences and best practices. The guide must cover: 1) Algorithm differences, 2) Audience demographics, 3) Content preferences, 4) Optimal length and format, 5) Cross-posting strategies, 6) Hashtag and caption differences, 7) Analytics and tracking, 8) Monetization opportunities, 9) Examples of cross-platform success, 10) Integrated strategy.