the topic has been explained very well by SER_GTR but a couple of important points have been missed
1st of all the position of the two engines in the engine bays of their respective cars
Note: The GA16DE sits in the left side of the engine bay.(while you are inspecting when you open the hood)
Note: The D15B VTEC sits in the right side of the engine bay. (again while you view from the front, while sitting in the car then the engine is in the left hand side)
you see where this comparison is heading the engines sit at opposing ends to each other. so they can't exactly interchange major engine parts b/w them.
2ndly look at the head gaskets of the two engines , they are miles apart.
GA16DE: 
GA16DE Head gasket (upper one)
D15B: 
D15B VTEC head gasket.
and as a final nail in this coffin the GA16DE is DOHC (twin cam, dual over head cam) and the D15B is a SOHC (single overhead cam) furthermore the bore and stroke of the two engines are also different , sure one is a 1.6 and the other is a 1.5
but a GA16DE has a bore of 76mm and a stroke of 88mm
and the D15B has a bore of 75mm and a stroke of 84.5mm
so even if you manage to make a Frankenstein out of these two engines it'll never run because all the camshaft timing ,ignition timing, piston timing will be wrong.
so to sum it all up its all as easy as fitting a round pig into a square hole.
thank you.
