This may be a simple solution but I do not know what is going on. I am reviewing the same image in Photoshop 2020 and Photoshop CC2014 side by side on my mac and the image is a bit softer in the 2014 version. I don't understand why the same image isn't the exact same in both versions.
As already explained above, you should judge and compare quality only at 100% magnification. Photoshop is doing quick scaling when viewed in any other magnification level for speed while sacrificing quality.