This study examines the interplay of power structures and selling formats in hotel-OTA partnerships using a differential game approach. We analyze optimal decision-making across four distinct scenarios, each defined by different combinations of selling formats and power dynamics. Our models derive equilibrium solutions, highlighting the effects on pricing, quality management effort, digital technology investment, consumer demand, room quality, and overall profitability. Numerical analysis validates these insights, offering practical managerial implications. Results show that hotels favor agency selling formats when consumers are price-sensitive, while OTAs prefer merchant formats. A stronger power position leads to higher profitability, while rising consumer expectations for room quality drives hotels to invest more in quality improvements. These insights offer actionable guidance for enhancing strategic decision-making and optimizing profits in a competitive market.