What the difference between Prog and psychedelic

People think of Simon & Garfunkel and only consider the massive hits but there was a lot more there.  Their 1968 album "Bookends" is very prog to my ears.  It begins with a solo guitar piece (like Crimso's Poseidon album) includes one of the first appearances on album of the Moog modular synth (patched by Bob Moog himself!), the song "America" which Yes of course covered, bizarre interviews with old people (very similar to the Godspeed You Black Emporer song  "Sleep - They Don't Sleep on the Beach Anymore"), and closes side 1 with a restatement of the opening solo guitar piece (like Crimso repeating variations of "Peace" throughout the Poseidon album).  Side 2 has some odd pieces along with the mega-hit Mrs Robinson.  S&G are a lot more musically interesting than history has painted them out to be.

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..And Prog is everything else, including the kitchen sink.

 

Bands like Yes, Genesis, and King Crimson are less Psychedelic regarding tones, time signatures, remain more in a Classical vain, covering up their small usage of sound effects ..although their attempt to change the speed of voices on tape, some usage of strings..for example on Yes' "The Prophet" is still more in a Moody Blues style if anything and all derives from the British Psychedelic genre more than the American. If any British musician took an influence from American Psychedelic, it was changed around and crafted to sound differently and it is hard to indicate. Jon Anderson often said that he was influenced by Simon & Garfunkel. Some people have a difficult time digesting this. Simon and Garfunkel recorded a more darker Folk style ..lyrically and musicially. Lyrically..the songs were about death and misfortune. Musically they were in dark minor keys with odd open string tunings or usage of capos. Yes have more of thAT American Folk influence than pure American Psychedelic fuzz tone guitar with Vanilla Fudge organ. The details are there to see...it just takes a little focus and patience.