[Ogre] Later edition rule changes

[Martin Thornalley]

I have second editions of Ogre and GEV (dating back to 1977 and 1978 
respectively) and was wondering what if any are the main differences between 
these editions and the later editions.  According to the ludography on the 
sjgames website there were 3rd editions of both published inthe 80s and 
combined editions in 1990 and 2000.  I know the maps were updated (in look 
and feel only) but were there any major rule changes between editions

Thanks in advance,
Martin