I imagine its related to demosaicing process.
A demosaicing (also de-mosaicing, demosaicking or debayering) algorithm is a digital image process used to reconstruct a full color image from the incomplete color samples output from an image sensor overlaid with a color filter array (CFA)
JPEG from Camera is shot as RAW and converted to JPEG in camera, based on some propitiatory demosaicing and denoising process from the camera manufacturer. You have no control over it, and I imagine since its done by the people who build the camera, its optimized for that camera.
PRIME denoising is just denoising, while demosaicing is done separately.
Deep Prime is demosaicing + demoseicing with the help of AI, but obviously DeepPrime XD is the same, just with better more accurate processing.
This example you are using is shot at base ISO, so its pretty clean image to start with. If you want to see a more noticeable difference, try higher ISO shots.
Like I said in the previous reply. Try the same scene with a different higher res camera and use the same settings in DXO and you will see what happens. That should demonstrate that if the scene and post processing application remain the same, but camera and lens change it must be the main reason behind what you are seeing.
"Typically, denoising and demosaicing are completed separately. DxO DeepPRIME adopts a holistic approach and combines the two steps into one, leading to exceptional performance.
The results are spectacular: DxO DeepPRIME removes noise and recovers information without losing detail in the image’s colors, creating more even and natural transitions. Compared to DxO PRIME, the DxO algorithm which previously set the standard for denoising in the photo industry, DxO DeepPRIME delivers an improvement of around two ISO stops.
DxO’s massive image database was used to train DxO DeepPRIME. Thanks to billions of carefully selected input and output samples, the artificial intelligence ‘learned’ the two fundamental operations of any RAW photo editing process: demosaicing and denoising." DeepPRIME - L'IA révolutionne le débruitage des images
“DeepPRIME removes noise and recovers information without losing detail, creating more natural transitions and textures. The results are spectacular, and as detailed below, the introduction of DeepPRIME XD pushes the boundaries even further. Compared to conventional noise reduction technology, DeepPRIME delivers the equivalent of an extra two stops of ISO. With DeepPRIME XD, it can be 2.5 stops, sometimes even more.”
On the analysis of RAW converters