Often, the biggest difference is build quality. Premium buds tend to feel sturdier and tend to be built with more premium materials. They also have a more premium look and feel to both the buds themselves and their charging case. In theory, premium buds should hold up better over time. Additionally, they tend to have more features such as ear-detection sensors and they pair with a companion app so you can upgrade the firmware (as well as tweak the sound and possibly customize the controls). Finally, while some cheaper buds have active noise cancellation, the performance of the noise-canceling and transparency modes tends to be better with more premium buds.