i was wondering whats the differences are with the el xr6 tickford engine and the series 1 au non vct xr6 tickford engine?

Bore size.
crank.
block.
oil pump.
sump.
rods.
pistons
head.
valves.
valve springs.
spring retainers and locks.
rocker gear.
cam shaft.

come to think of it, there is no one component that will interchange without the need to changer other stuff. EG: you can swap the heads over but you need and entire head assembly, you can't fit AU valves into and EL head without changing the guides ect.