A "LED monitor" is a "TFT Active Matrix screen" with LED backlight.
You can thank Samsung for coining the phrase "LED HDTV" which then migrated to "LED monitor"; thus causing some confusion in the market.
A "LED HDTV" / "LED monitor" both use LCD panel, but uses LED (a.k.a. WLED) backlight instead of traditional florescent backlight.
LED (a.k.a. WLED) = Blue LEDs with a yellowish phosphorus coating to imitate white.