quite a few differences........
series two had a revised cooling system (radiator cap and surge tank, S1 was a pressurised system)
Coolant hose at rear on s1 front on s2 with bleeding screw... (sounds painful)
ecu should remain the same,
s1 had no bellmouth in the intake s2 did
early s1 had a higher stally then older models
s1 made 125kw, vp motors make 127kw...
series ones had different fittings for manual and auto...
BUT! to answer your question, if your changing the motor, ensure you get the ENTIRE cooling system, hoses (new ones), coolant overflow bottle, radiator etc. and yeah the motor....
Any more questions?
just wasnt sure what you meant by differences....
Dave