what is the different?.

I await your answer BQ.

Development is moving your pieces off of the squares they started on (excluding pawns). Strategic positioning of pieces is placing them somewhere meaningful, usually for a tactical sequence or more control of the board. So you can develop your knight on b1 to a3, but usually it doesn't do much there. 

Another way to think of it is tat strategic positioning of pieces is just better development with a purpose. So all strategic positioning is development, but not all development is strategic positioning. 

Oh no its happening again!

I always heard it's when a girl blossoms into a woman.

Thank you.  So, you said that strategic positioning of pieces is just better development with purpose right?, so, my question is ''can you give me an example of this''?.

I miss me too.

what is the underlying essence of strategy in chess?.

Beer!