just quickly-
wrx ra = standard wrx with a few RA bushings here and there, heavy centre diff, short ratio box, short shifter and lsd, climate control, airbags, nothing really "sti" about them.
an sti ra has the dccd, r180 rear, cams/heads/crank/etc,
ecu, + all the other sti fruit.
a sti ra vlim has all that + radio, climate control, airbags etc