Is the body of the M3 Pro bigger than the M3 or just the camera/gimbal are bigger?  Comparing the dimensions on the DJI website there is difference in the measurements but I assume it's just because the camera protudes more and is a bit taller to keep it from touching the ground.  Who has both and can confirm they're the same chassis and just different camera? Thx.

Yes, they are the same chassis.

The bodies are the same. But there are a few minor differences with the rear arms.
The motors are mounted a little higher, so they stick out a little higher. And the angle that the rear arms rotate is slightly different, so when folded they are slightly wider. And because the motors are mounted higher in the arms, they create more room for the camera, making the whole drone a little bit taller when folded.

from dji.com

Mavic 3:

Dimensions (Folded/Unfolded)
Folded (without propellers) 221×96.3×90.3 mm
(Length×Width×Height)
Unfolded (without propellers) 347.5×283×107.7 mm
(Length×Width×Height)

Mavic 3 Classic:

Dimensions
Folded (without propellers): 221×96.3×90.3 mm (L×W×H)
Unfolded (without propellers): 347.5×283×107.7 mm (L×W×H)

Mavic 3 Pro:

Dimensions
Folded (without propellers): 231.1×98×95.4 mm (L×W×H)
Unfolded (without propellers): 347.5×290.8×107.7 mm (L×W×H)

skyscope Posted at 5-9 14:54
The bodies are the same. But there are a few minor differences with the rear arms.
The motors are mounted a little higher, so they stick out a little higher. And the angle that the rear arms rotate is slightly different, so when folded they are slightly wider. And because the motors are mounted higher in the arms, they create more room for the camera, making the whole drone a little bit taller when folded.

Thanks all for the confirmation. Expecting my M3Pro today. Sold my M3 yesterday so not able to do a side-by-side on compare.

Hi there. Thank you for reaching out. The DJI Mavic 3 Pro is much bigger than the DJI Mavic 3 aircraft. You may refer to the specification posted by The Saint above for your reference. Should you have other inquiries, please don't hesitate to reach us. Have a nice day ahead!