One thing i’m often asked by other photographers, is what the difference between the Save As and Save For Web functions in Photoshop are?
To that my answer is typically, Very Little!

In all honesty, the biggest difference between the two are that in Save For Web actually strips out all of your images EXIF Data.

EXIF DATA
For those of you not familiar with EXIF Data, this is the information under the hood which can be accessed from within Photoshop by going to File / File Info and displays such data as the time and date the picture was taken as well as the Camera and Lens it was shot with and most importantly what shutter speed, iso and fstop the image was taken at.

SAVE AS
The standard Save As gives you a wide variety of file formats to save to, but for web and email purposes you’ll want to choose JPEG and as long as your photo has been converted to sRGB prior to saving, it’s not imperative that you leave the check box selected to include the ICC Profile as the sRGB info has been embedded into the file and most all browsers nowadays will read the sRGB Data and display it properly.

If for some reason your image looks funky, go back and make sure you have converted your image from AdobeRGB to sRGB.

With Save As, you are presented with a simple Slider to set the amount of compression you’d like to apply to the image and if you leave the Preview Box checked you can view how your image is going to be affected by the compression in realtime. Other than this, that is about as much control as you’ll have over your image.

SAVE FOR WEB
Save for Web presents you with it’s own fancy dialog box which provides many more options for selecting the type and amount of compression to be applied to you image. The quality slider is much more granular and you also get a realtime presentation of how your image will be affected.

There are 4 views to choose from Original = The file in it’s original state, Optimized = The current file with compression applied and then 2 up and 4 up which allow you to set each quadrant to a different compression and compare to get the best file possible. In the bottom left corner you will also find the size of the file upon output with it’s approx download time based upon connection speed. These modem speeds can be changed in the top corner by clicking on the lone arrow and selecting one that is more appropriate for your target audience.

When Should I Use One Format Over the Other
There are no hard and fast rules, but i’ll provide a few examples below that might help you out.

Creating Images for Your Website
Save For Web

Sharing Images with Others, but want to hide time, date and other exif data
Save For Web

Sharing Images with Others, but want to share time, date and other exif data
Save As

Total Control over File Compression Settings
Save For Web

Day to Day Usage
Save As

Ok there you go, a quick overview of the Save A vs. Save For Web dialog boxes in Photoshop.
If you have questions or comments please feel free to leave them below.