LCD with CCFL backlight (LCD monitors) :
slightly higher power consumption
low lamp life
lamp life reduce with no. of on/off cycles, low brightness.
LCD with LED backlight (LED monitors) : low power consumption
long lamp life, on/off cycles doesn't affect lamp life
high brightness
wide possibility of brightness adjust.
both monitors uses same LCD panels. only back light difference.
normally LED-LCD monitor uses 18~20W power while LCD-CCFL uses 30~40W. (For 20 inch economy class monitors)
this is my personal idea as my knowledge. no a copy paste.