This is quite a common experience, and is a frequent question on photography discussion groups. To get a flavor of the situation, if you Google {"camera raw" "looks different" "photoshop"}, I bet you will see hundreds, if not thousands of discussions of this topic, so don't feel bad, LOL.
Unfortunately, this type of inconsistency in file viewing can arise because any or all of the following factors can be present in your particular case:
1. It's easy to accidentally change the default RAW conversion settings in ACR (or LR).
2. Every different RAW converter has different default conversion settings, so what you see in ACR is almost guaranteed to look significantly different from what the same raw file might look like using the default settings in "Phase 1", OnOne software's brand new release, DxO's raw converter, "Raw Therapee", Silkypix's RAW converter, Nikon's NX or Canon's DPP bundled editing progams, etc. etc.
3. To make matters worse, the raw converter software in the camera that converted the raw data from the sensor to an sRGB JPG for output has its own easily changed settings (accessible through the camera's menus). In addition, the camera takes a slightly different processing path to convert RAW images to send to the camera's screen for immediate display. The latter is because all displays differ in their color responses.
4. Your computer (or tablet or phone, etc. etc.) needs some way to display raw files in, say, windows file explorer. Usually the codec simply just extracts the small sRGB JPG that is bundled inside most raw files and displays that. However, a few codecs realize that this approach doesn't provide enough resolution if you want to see a larger preview, and instead, some codecs try to do an actual RAW conversion themselves. Just like in #2 and #3 above, each of these codecs have their own algorithms and settings, the results of which may or may not look like the results of any other RAW conversion method.
5. As I'm sure you know, even something as common as a JPG can be in various color spaces. sRGB is the "safest" (ie, most often rendered correctly for viewing), but Adobe RGB and ProPhoto are other very common spaces. Many high end cameras have the option of switching the camera-generated JPG between these variants. Unfortunately, many software products still don't have a clue about how to display an Adobe RGB or a ProPhoto JPG, so they throw up their hands and simply render it as if it was an ordinary sRGB. This can produce horrible looking versions of the file data. Such software is described as being "not properly color managed" or "not CM compliant".
Unfortunately, it is well known that Windows' "Photo Viewer" was in this category for many years. I think they updated it in Win 8, and maybe again with the release of Win 10, but to be honest, because of its well known limitations, I rarely use it, and haven't been following its evolution through the years.
In contrast, ever since color management standards were introduced a decade or so ago, Adobe has been the leader in this field and displays all these different color spaces correctly, so if there is any question about the color space of a file, I will always use one of Adobe's products to view it, most commonly, either Bridge, Lightroom, or PS itself.
6. I'll stop after mentioning a final, incredibly common problem that can produce the type of inconsistency you experienced, and that is the issue of monitor profiling and calibration. No monitor, even the most high end ones, ever reproduce colors properly, so, if one is serious about their photography / photoshop work, you should buy the very best monitor you can afford, and then measure its color accuracy and generate what amounts to a translation table to further refine its color performance. This translation table is called an "ICC monitor profile" file. Both windows and macs can install these at the system level, so they are trivially available to any program that wants to do color "properly". As usual, Adobe almost always gets it right and uses these monitor profiles in almost every file viewing situation, whereas, some programs simply ignore these. Of course, with yet another case of "some do" and "some don't", the user is left with possibly inconsistent results as they go from one software package to the next.
I could go on for pages and pages more on this irksome topic, but you probably simply want to know what to do. Here are my recommendations:
1. Until you become very knowledgable in color management, *** ALWAYS, ALWAYS, ALWAYS*** do everything in your power to stay in the sRGB color space and you are only using properly color managed software for image viewing. Many of the following recommendations are simply specific cases of this.
2. Either (a) completely restore your camera to its factory default settings; or, (b) or go into the menus and make sure that even if you intend to use RAW files most of the time, it is always producing sRGB JPGs, and no odd settings or "styles" are being applied. You don't need a potentially confusing inconsistency to enter your workflow right at the starting step of image production.
3. In ACR, restore the current default conversion settings to their factory defaults. If you don't know how to do this, Google it.
4. If you have ever played with the color management adjustments at the level of the OS, either go back and make sure the monitor profile for your system is set to its "do-nothing" default, OR, if you own and use monitor profiling and calibration hardware, run it again, and make sure that the monitor profile it generates "sticks" after a system reboot. Confirm this by including the date in the file name for each profile your calibrator generates.
5. Never use Windows Photo viewer unless you first check that the version you have is a recent, properly color managed version. I think this boils down to using Win Photo Viewer only in Win 8 or 10, but you should check for yourself when Microsoft made the improvement.
6. Only use Adobe's products to view images and help you make critical editing decisions about brightness and color.
7. If you are using Photoshop, go into the "preferences" and color management areas in both Photoshop proper and ACR, and make sure that (a) your working color space is always sRGB; (b) all incoming files are automatically converted to sRGB (including the output from ACR); (c) make sure that whenever you output a file, it is always in the sRGB color space.
8. Learn how to use Adobe Bridge (or some other equivalent software) to regularly check the color space of any file that you produce or concerns you.
Unfortunately, this is not a simple topic. There is a lot more to discuss, but I will stop here. If you want to learn more, Google {"camera raw" "looks different" "photoshop"}, and {color management basics} and read yourself to sleep for the next few weeks, LOL.
HTH,
Tom M
PS - FYI, I'm heading out of town in a couple of days and will be gone for most of December, so, if you have any questions ...
