what is the difference between a electric piano, electronic piano, synthesizer and midi keyboard?

Hi,

An electric piano (Rhodes) is somewhat like an electric guitar, hammers strike short piano strings, sound is taken with tiny mics.

Big pop sound.

An electronic (digital) piano is generally made of audio samples recorded from a real piano. Sometimes may play clavichord, etc.

Most home leisure thing.

A synthesizer is a big word, but in vintage times, it was the only one electronic sound, most often monophonic Moog, ARP, ...

nowadays, you got Yamaha DX series, for example, that created sound from many oscillators and complex algorithms : FM Synthesis.

Today, most synthesizers are sample based one can play any instrument, even drums and more funny ones like bird singing, helicopter and so on.

Most today's keyboards are Midi compliant. So you may have a digital piano or a tiny or a big synthesizer with midi interface.

Midi interface may be used to record performance with a sequencer or to drive expanders (sound generators).

You may also have a keyboard with a midi interface (and often a lot of knobs) but no sound output, that's what we call a master midi keyboard. you've got to plug it to a computer or an expander to hear something.

Hope this helps.

A regular acoustic piano will always make the normal piano sound better and fuller when kept in tune. However, an electric keyboard is portable, makes alternate sounds, can be amplified, can be plugged into a computer to record with and is perhaps generally more useful for a musician. Just in-case I misunderstood you and you were asking the difference between an electric piano and an electric synthesizer, there's no difference. EDIT: Also note that an electric keyboard does not have to be tuned where an acoustic piano has to be tuned about once a year for a casual musician.