Some cards state "discard.." while others specifically state "discard FROM PLAY"
So while "discard" is pretty well defined as put the card in question into your discard pile - what exactly does "discard from play" mean??? In old edition of the game we interpreted it as put it back into the "market", but this is no longer clear as the second edition rules defines the discard pile as "not in play", so "discard from play" would mean (under the second edition rules) a plain "discard" as the discard pile is not defined as "in play" (example: Elixir of life")
"Discard" with nothing else means put the card in question from your hand into your discard pile.
"Discard from play" or "discard from in play" means put the card in question from the table in front of you into your discard pile (or the Town Discard if it's a Town card).