GeoTools, as a project, has been around for approximately 7 years. It now exists as two separate versions; known as GeoTools 1 and GeoTools 2 (GT1, GT2).
The current convention (especially on this site) is to refer to GT2 as GeoTools 2 or just GeoTools.
The older version is now to be known as GeoTools-lite but you will still see it being called GT1 from time to time.
This site is dedicated to GeoTools 2.0. However, because the old version still has a large number of users and wide application (due to the fact that it works with Java 1.1) we keep an active site running at lite.geotools.org.
Hope that clears things up more than it confuses!