there's a small discussion going on at the P99 forums about how "classic" content on EQMac was different than true classic in some ways. i only played on EQMac for a short while... but two things i recall were that on EQMAc the Nybrights in LFay dropped Rusty weapons instead of Bronze, and the spiderlings in Field of Bone were all single pulls.
i've heard other stories of various rare NPC spawns and whatnot functioning differently on EQMac than they did in classic, but i don't know specifics. is there anything you guys remember?
I think the discussion on P99 and your question could potentially rooted from a fundamentally different place. EQ Mac, as you surely know, is a PC port shortly after the release of PoP. There are loads of things in classic and Kunark that are not as they were in 1999, simply due to the fact that Sony had revamped some loot tables etc from Vanilla zones by this time. This could and probably does explain most differences between EQ Mac and true classic content. Your question, however, seems to be suggesting that if you took PC Mac circa 2003 and EQ Mac of the same era, that there would be slight variances due to some quirks in the port or something lost in translation. I honestly believe that to be the case in some regards, especially on the pathing side. I can think of several zones on EQ Mac which had mobs which had some bug in their pathing route which cause them to pop from the sky at the zone line and being pathing from there. I can't say for certain, as I didn't play during the PoP era on live, but in 1999 I did not remember that or several other quirks of EQ Mac being present.
In terms of the ability to port to a Mac code base, I am by no means a programmer, but I would think that attributes of the game would fall into one of two pools:
Ability to Match Perfectly:
Spawn Locations
Mob HPs
Mob damage ranges
Mob abilities etc
Spawn locations
Visual Zone Geometry
etc
May not be 100% Accurate:
Zone Geometry in terms of line of sight/bolts/agro etc
Ability of mobs to move around their pre-prescribed pathing
Latency
My suspicion is that the second bucket is something that probably an area that may have actually required some recoding which could cause slight divergences in live to Mac. I would assume that the first bucket is stuff that they would have no reason to change. I could be totally off in this assessment, but based on the few months I played there, I did think there was a slight difference in just how you and mobs moved through the world. The combat etc seemed dead on, however.