Both terms mean about the same, although smidgeon (sometimes spelled smidgen) means a tiny, almost undetectable amount, is usually a scosh.
Shel > [Original Message] > From: E.R.N. Reed > >A "scosh" is a term that means "just a little," but by no definite amount. > > > > > > > How does it relate to a "smidgen"? More, less or about the same? > > ERNR > genuinely interested