LoD is the exact same story / quests as vanilla, but with an extra act tacked on to the end. The main differences you'll see in the first four (original) acts are no persistent mercenaries and a smaller stash (plus no LoD loot, less classes to choose from...). I don't know who told you the expansion is a different story, but it isn't.
The patches add lots of cube recipes, new items and lots of gameplay tweaks (like skill synergies and rebalancing). To get the patch all you have to do is connect to battle.net (it downloads and installs automatically). Be sure to check out http://www.battle.net/diablo2exp/ if you want to look up any game information (sets / uniques / formulas / rune words...).
LoD is the exact same story / quests as vanilla, but with an extra act tacked on to the end. The main differences you'll see in the first four (original) acts are no persistent mercenaries and a smaller stash (plus no LoD loot, less classes to choose from...). I don't know who told you the expansion is a different story, but it isn't.
The patches add lots of cube recipes, new items and lots of gameplay tweaks (like skill synergies and rebalancing). To get the patch all you have to do is connect to battle.net (it downloads and installs automatically). Be sure to check out http://www.battle.net/diablo2exp/ if you want to look up any game information (sets / uniques / formulas / rune words...).