When we play with Ed1 boards and pieces, we used printoffs of Alpha+3 rules and setup, which are virtually identical to the printed, Second Edition layouts on the boxes. If you have a copy of Ed1 and those printouts, you pretty much have the Ed2 game, with some minor inconvenience of having to refer to the papers. Panther covered the rule and map tweaks that I know of.
So the only other differences playing with a ed1 copy are;
AAA rules were changed from ed1 and ed2, but they are in A+3 as in 2ED. The sculpts however, are mega confusing. AAA guns for Germany look like artillery pieces, and are very fragile and spindly. This has thrown me several times. The Ed2 added better artillery and better AAA sculpts.
The board, I think, was slightly tweaked because there is an edge that can be a little misleading as to where the territory is. also the canada change mentioned. The boards between the different runs also seem to line up a bit oddly depending on which ones you have.
All new ANZAC sculpts were added to 2ED, most people think they are silly because the infantry are gigantic, and the cruiser and destroyer confuse some people as reversed.