^^ THe E series have a LED back-light and G series are the usual CFL back-lit LCD monitors . Also E series E2220 HD has a HDMI port will the G2220 HD lacks it and is limited to the DVI connector.
The image quality is more or less the same. Another option you can look at is the Dell ST2220L, HDMI connector + LED back-light and the usual Dell assuarance all your for ~ 8500/-. A bit pricey but worth it.