Raw Image(AVCapturePhotoOutput) CMSampleBuffer(AVCaptureVideoDataOutput) difference?

Question

I'm working on getting a raw image from avfoundation.

I have a understanding of general pipeline of digital image.

1. image sensor
2. bayer filter
3. demosaicing.

My goal is getting a image as raw as possible.

I found out that using AVCaptureOutput, if device support raw pixel format, I get output as raw format in callback function -

func photoOutput(
     _ output: AVCapturePhotoOutput,
     didFinishCaptureFor 
     resolvedSettings: AVCaptureResolvedPhotoSettings,
     error: Error?)

but what is difference between AVCapturePhotoOutput in this function and CMSampleBuffer in the AVCaptureVideodDataOutput callback function:

func captureOutput(
    _ output: AVCaptureOutput,
    didOutput sampleBuffer: CMSampleBuffer,
    from connection: AVCaptureConnection
)

this is my guess..

1. CMSampleBuffer is image buffer which after all 1,2,3 step(after demosaicing)
2. output from AVCapturePhotoOutput callback function(with raw format supported) is after step 1-2(after bayer filter)

is this right?