What's the difference between a Theodolite and a Transit Level?

My dad left me a nice transit (David White Site Boss 8085, with plumb bob and professional tripod) which I've decided I'll never use. Researching online what it's worth, I see these described as both "transit levels" and "theodolites."

Cannot determine which it is -- both? How should I list it?

Even this doesn't really clear it up for me.
http://www.engineersupply.com/Transits-Theodolites-Total-Stations-Levels.aspx

I found this:

A Theodolite is a instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a tool used in the surveying and engineering industry, but theodolites have been adapted for other specialized purposes as well. A theodolite consists of a telescope mounted movably within two perpendicular axes, the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arcseconds. The measurements are typically recorded by hand as they are not recorded by a computer or data collector.

A transit is type of theodolite that features a telescope that can "flip over" which would allow easy back-sighting and doubling of angles for error reduction. Some transit instruments were capable of reading angles directly to thirty arc-seconds. In the last 50 years, transits have been known as a simple form of theodolite with less precision, lacking features such as scale magnification and mechanical meters. The importance of transits has been decreasing since more compact, accurate electronic theodolites have become widespread tools, but transits still find use as a lightweight tool for construction sites. Please note that some transits do not measure vertical angles.

Yeah, I think I found that too.