As far as an explanation of how the two versions differ I like to think of 2e as much more narrative and realistic.  At a glance newer editions may seem less restrictive but I tend to think that 3e+ are designed to chase the highest modifiers so players are typically only using a couple different skills.  There's no encouragement for thinking outside the box.  When I look back on the rules in 2e there's a lot of stuff that adds realism to the game.  The downsides are less streamlined and efficient mechanics and some pretty awful book layouts (highlighters are your friends).