I believe what you are seeing here is the result of differing FOV caused by different image sensors in each camera, albeit both using the same lens.
The resolving power of a camera comes down to the lens selection and the image sensor size and resolution which are in fact different in your case.
For example, the 2CD2386G2 with a 4mm lens has a horizontal FOV of 87degrees whereas the 2CD2385FWD-I with the same 4mm lens has an FOV of 79 degrees although both cameras are 8MP.
The result of the 2CD2386G2's wider FOV is that there are less pixels per metre across the horizonal and vertical image than you used to have with the 2CD2385FWD-I.
If you compare two identical scenes from both the 2CD2386G2 and the 2CD2385FWD-I you will notice the 2CD2386G2 will show more of the scene than the 2CD2385FWD-I for the same lens.
When you zoom into part of the image, the result will be that the camera with the wider FOV will not be able to resolve fine details to the same extent as a camera with a narrower FOV for the same image sensor resolution.
If you look at your side by side comparison pictures you will note that to get the same size image of the signpost, the 2CD2386G2 is zoomed to 13.5X while the 2CD2385FWD-i was only zoomed by 11.8X.
This suggests that I'm right and is at the very least part the reason you are finding the 2CD2386G2 is not giving you as clear an image of distant objects when zoomed in.
I also replaced a 2CD2385FWD-I with a 2CD2386G2 both with 4mm lens but I knew at the time I would be sacrificing pixels per metre. The trade off was much better low light performance, Acusense technology and much better dynamic range than the much older G1 series 2CD2385FWD-I.