I usually use F12 to take a Steam photo in TSW3. But I found Ctrl F12 takes photos too but not sure it is Steam? As it takes the photo/screenshot differently....
It's not a steam feature, ctrl+f12 is the game's built-in screenshot feature, which is much higher quality than steam
F12 is steam, it will include the HUD if you have it turned on, and if you have motion blur or TAA etc then those effects are retained into the shot too. It will take the shot at the resolution of the game as it runs. Ctrl-F12 is the built in screenshot feature, you can choose what resolution this is in settings - normal is a 1080p shot and high res is a 4k shot, regardless of what res you play the game in, it essentially re-renders the scene at the higher resolution meaning you can get some lovely 4K shots out of the game even if you don't have the equipment to run it at 4K all the time. This mode also auto-excludes the hud from shots, and as its a fixed moment in time re-rendered, you don't get any blur from motion blur or TAA etc - which may or may not be a good thing depending on what you want. I usually use Ctrl-F12, but sometimes I want a more natural shot including blur and other effects and then I use the steam facility. Matt.
IIRC another difference is that the CTRL + F12 screenshots are uploaded to your Dovetail profile if you are logged in, while the F12 (Steam) screenshots can be uploaded to Steam (by using the Steam UI after you play).