I am always confused between both of these two. I know both signals low speed or high AOA
Low energy warning is a function of Flight Augmentation Computer (FAC). It monitors aircraft’s flight path and warns if speed is about to decay below the threshold where power is needed in order to maintain positive (ie. climbing) flight path with pitch control.
Alpha floor is provided by auto thrust (A/THR) - (commanded by FAC), which sets full thrust (TOGA) regardless of pilot input if angle of attack rises above pre-determined angle. The threshold depends on aircraft configuration.