RSS= Real Simple Syndication is one of six or so definitions for this highly usefull way of putting information on the web. There is even something called podcasting which could be tought of as RSS's answer to video and/or audio.
Blogging= What you do with RSS.
RSS Reader= What you need in order to read and retreive rss feeds
There are 7 versions of RSS. 0.90.0.91,0.92,0.93.0.94,1.0 & 2.0, Three are owned by UserLand, one by Netscape, and one by RSS-DEV Working Group. 2.0 is the latest and 0.90 is the oldest(the Netscape Version)