Today’s Question: Regarding Adobe Camera RAW and Photoshop’s Camera RAW filter — what is the difference? I usually open Photoshop, then select Browse in Bridge. When I then open a RAW image, which processor am I using? When I open an unlayered TIFF image using that procedure, a Camera RAW dialog box automatically appears — is that Adobe’s Camera RAW or Photoshop’s filter?
Tim’s Quick Answer: The basic difference here is one of timing. Adobe Camera Raw is a tool for processing RAW captures, though it is also able to process TIFF and JPEG images with the same adjustments. The Camera Raw Filter in Photoshop provides the same set of adjustments, but for images that have already been opened in Photoshop (and therefore have already been converted from the original RAW capture format if applicable).
More Detail: The Adobe Camera Raw (ACR) feature in Photoshop was originally a plug-in that was added on so that RAW capture formats could be converted to a proper pixel-based image format using Photoshop. Prior to the release of ACR, it was necessary to process your RAW captures using other software before working on your images in Photoshop.
More recently, Adobe updated ACR to enable it to open and process TIFF and JPEG images, in addition to RAW captures. Obviously if you process a TIFF or JPEG image in ACR you aren’t achieving the benefits of working with a RAW capture, but this support provided some benefits for a streamlined workflow. In your case this option is enabled, which is why your TIFF image is being opened via Adobe Camera Raw upon opening in Photoshop, even though ACR is not actually required for opening a TIFF image.
Even more recently, Photoshop CC was updated to include a Camera Raw Filter, which features all of the adjustments available in ACR, which can be applied to any image you can open in Photoshop. This primarily provides a workflow advantage for those who are more comfortable with the ACR adjustments compared to other options in Photoshop. It also provides a benefit in terms of improved adjustment options, such as noise reduction that is better than the other filters included in Photoshop.
So, again, the core difference here is that RAW captures would need to be processed by ACR upon opening the image in Photoshop, while the Camera Raw Filter can be used with any image already opened in Photoshop.