Sony has quietly appended an "A" to the product model names of the Sony Alpha a7R IV and Sony Alpha a7R III mirrorless cameras.
The primary changes this update brings appear to be the LCD resolution increasing significantly to 2,359,296 dots from 1,440,000 dots, with the battery life dropping by an insignificant amount, along with the USB spec improving from USB 3.1 to USB 3.2 on the a7R III.
Watch for the new a7R IV and a7R III revision A to arrive at B&H.