The camera now has a 1/1.3" sensor (up from 1/1.7") and can record gyroscopic data. Also, it has a tougher case and other improvements - but a higher price too.
DJI Osmo Action 3 Camera Standard Combo
DJI Osmo Action 3 Camera With Up to 4K/120fps Video Recording Launched
DJI Osmo Action 3 action cam boosts sensor size, battery life & cold-weather performance - Bikerumor
Smartprix on X: DJI launches New Osmo Action 4 Camera Features: -2.25” Back & 1.4” Front Touchscreen Display -Larger Sensor 1/1.7” & pixel size- 2.4µm -155° FoV with f/2.8 aperture lens -Record
DJI Osmo Action 4 Review: Big Sensor, Big Impact
DJI Osmo Action 4 camera Lights Up w/ Massive New Sensor - Bikerumor
DJI Osmo Action 4 vs DJI Osmo Action 3: What's the difference?
DJI Osmo Action 4 camera takes on GoPro with new larger image sensor - BikeRadar
DJI Osmo Action 4: A camera that goes beyond the limit - PinoyTechBlog - Philippines Tech News and Reviews
NEW LAUNCH】DJI Osmo Action 4 - Action Camera, 1/1.3-inch Sensor & Stunning Low-Light Imaging (PRE ORDER)
DJI Osmo Action 4 Vs GoPro Hero 11 Black: Which Is Better?
Ready, set, action! DJI announces the Osmo Action 4: Digital Photography Review
DJI Osmo Action 4 vs DJI Osmo Action 3: What's new?