shlucho is a passive present verb nishtalcha is a past nispael. best with another example. boruch is a passive verb. Meaning hashem is blessed without anyone doing anything. It is a state of being. Like tsorua is being in the state of tsoraas. A hispael is when someone does something to himself. A nispael is when something is done to you similar to a niphal. nisbarech is someone who has been blessed. An action has happened and you are quoting the action. boruch you are quoting the present state not an action.