In terms of results, you can get the same from Vegas that you would in Color, just with some more work required.
The real difference is in the workflow. While Vegas works with color correction applied to individual clips or whole tracks, Color is all about creating looks that can be applied to similar sequences of clips very quickly, and then fine-tuned shot by shot. Color also has easy access to masking tools.
This makes Color very fast and efficient while grading an entire project. I find Vegas a lot slower if you try to just work on your project the way it was arranged as you edited it, but if you specifically set a project up for just grading, grouping similar shots together on their own track, and using lots of tracks, you can work in a style similar to Color.
I am always making a judgment call: is it faster to just do the work in Vegas, or to take the time and space to output it and move it over to a Mac for Color. I usually just stick with Vegas.