the eMac was introduced after the G4 iMac was introduced. That machine had a flat panel screen, and so was more expensive. Apple introduced the CRT based eMac as a low cost alternative for schools (CRT's are also more durable) The public like them, so apple made them available to everyone. They specs were similar to the G4 iMAcs. Of course, the iMac went on to get a G5 processor and then an intel processor. The eMac went no further.
If you want to compare specs, check out everymac.com