Here's a color pic of Endora from the first season. As you can see, her gown was a pale olive green color, but for the colorization, they made it bright green and purple like the gown she wore during the color seasons.
The colorized versions will have different language tracks that the b&w will not. So, for example, you can hear Samantha speak in Spanish. I think they did this for the syndication of the colorized episodes a few years ago. This just answered another question that other people (including...