In-ear earbuds sit inside your ear canal to create a seal that helps improve sound quality, emphasize noise-canceling, and provide passive noise isolation. On the other hand, open-ear earbuds leave your ear canal open while still transmitting audio to your ears through various methods. 

Some earbuds, such as the Apple AirPods 4, feature a semi-open fit, which sits somewhat loosely without creating a full seal in your ears, allowing them to feel less constricted. However, because of their lack of a seal, these earbud types may struggle to create full and intimate audio performance.

Brands also sell fully open-ear models, like the Soundcore Aerofit 2, that don't block any ambient audio. These earbuds sit above your ear and transmit focused sound waves from specialized drivers.

Bone-conducting headphones, like those from Shokz, are another type of open-ear option. These headphones use sound pads designed to transmit audio through your jawbone. All open-ear earbuds have limited use cases but are prized by active users for their ability to let in environmental sounds naturally.