Single Echo Filter and Flanging any difference ?

Flanging is nothing but an audio effect generated when two identical signals are mixed together with a small delay period.

Single Echo Filter uses the signal and its first reflection of the direct signal(first harmonics) arriving at the destination. Here the amplitude of the first reflected signal is lesser than the direct signal.

If the amplitude of the first reflected signal of the single echo filter matches the amplitude of the direct signal, then conditionly flanging and single echo filter are same and if not then they are different.

Effects Pedals are electronic devices that modify the tone, pitch, or sound of an electric guitar. Effects can be housed in effects pedals, guitar amplifiers, guitar amplifier simulation software, and rackmount preamplifiers or processors. Electronic effects and signal processing form an important part of the electric guitar tone used in many genres, such as rock, pop, blues, and metal. All these are inserted into the signal path between an electric instrument and the amplifier. They modify the signal coming from the instrument, adding "effects" that change the way it sounds in order to add interest, create more impact or create aural soundscapes.

Equalization means boosting or reducing (attenuating) the levels of various frequencies in a signal. At it's most basic, equalization can mean turning the bass/treble controls up or down. Advanced equalizers have fine controls for specific frequencies.

Common uses for equalization include correct signals which sound unnatural 

Compression means reducing the dynamic range of a signal. All signal values above a certain adjustable threshold are reduced in gain relative to lower-level signals. This creates a more even signal level, reducing the level of the loudest parts.