Welcome to the forum!
This link should help you.
http://www.rcuniverse.com/community/glossary.cfm
I have never own the TR-15 but at one time was thinking about buying one. After talking to RCers that have been in the hobby for sometime I decided against it. I all so do not recommend a RTR and building a kit should not be a problem and you will end up with a much better vehicle. I all so feel you would be much better off with a 1/8 buggy.