The first difference with the others captors is that SnagIt allows you to capture any video image without having to configure RGB options in the video player.
It is one of the most completes screen captors. You can choose 12 established patterns to capture images, you ca capture the full screen, a part of it, a web page (scrolling it automatically),... and if you don't like any of them, you can custom your own one.
Once you have your captured screen, you can use the built-in editor and apply it lots of effects, from edging it, to paint and write on it. Of course you can add watermarks to the image. And the editor can be used with any image, it doesn't have to be captured with SnagIt.
In addition, it includes a photo organizer, so you will not miss any picture.
You can capture the images as jpg, bmp, gif, thm,... and you can use it to convert your own photos.
All this is housed in an intuitive and easy-to-use interface.