bore and stroke are differnent.

318 is internally balanced 360 is externally,

and the motor mounts are different for la mounting

318 is 2 3/8 between mounting points on both sides

360 is 2 3/8 on pasenger side and 2 on driver side

So if you go to a junk yard or swap meet you can check the motor to be sure the guy is selling you the right motor.
(we dont use these mounts for our trucks guys,(old mopars.))

 

For a fast, visual verification, just check the balancers. They are different, the 360 is thicker.