both are lcd panels.
led refers to led backlighting which is typically around the edges (edgelit).
other panels are ccfl backlit behind the entire panel.
the only thing you gain is power savings.
contrary to what jrock247 stated, just having led backlighting will absolutely not give you any difference in quality or refresh rates. in fact, buying a cheap monitor with led backlighting can give you a worse picture due to the fact that white leds are not used. instead they coat blue (i believe) leds with white phosphorous to make them appear white. this can cause a blue/purple hue to your monitor which you can probably adjust out with propper color adjustment.
panel type (tn,va,e-ips,s-ips,p-ips,h-ips) affects your refresh rate and...