The Bose QuietComfort 35 II and the Bose QuietComfort 45 are both noise-canceling headphones from Bose, but the QuietComfort 45 is an upgraded version with several improvements over its predecessor. Here are some of the key differences between the two models: 1. Design: While both headphones share a similar design language, the QuietComfort 45 features a slightly more refined design, with a cleaner look and a more streamlined headband. 2. Noise Cancellation: The QuietComfort 45 boasts an improved noise-canceling technology called Aware Mode. This mode allows users to hear their surroundings without having to pause their music or take off their headphones, offering a more seamless listening experience compared to the QuietComfort 35 II. 3. Sound Quality: The QuietComfort 45 has been engineered for better audio performance, delivering a more natural and balanced sound signature. The improvements in audio quality provide a more immersive listening experience compared to the QuietComfort 35 II. 4. Battery Life: Both headphones have similar battery life, offering up to 20 hours of wireless playback with noise cancellation enabled. However, the QuietComfort 45 has a quicker charging time, taking only 2 hours to fully charge, compared to the 2.25 hours required for the QuietComfort 35 II. 5. Bluetooth: The QuietComfort 45 comes equipped with Bluetooth 5.1, providing better wireless performance, improved range, and more stable connections compared to the Bluetooth 4.1 in the QuietComfort 35 II. 6. USB-C Charging: The QuietComfort 45 has switched to USB-C for charging, in line with the industry trend, making it more convenient and future-proof compared to the micro-USB charging port found in the QuietComfort 35 II. Overall, the Bose QuietComfort 45 is an improved version of the QuietComfort 35 II, with enhancements in design, noise cancellation, sound quality, and connectivity. If you're looking for the latest and most advanced features, the QuietComfort 45 is the better choice. However, the QuietComfort 35 II remains an excellent option for those seeking comfort and effective noise cancellation at a potentially lower price point.