Morrowind = Oblivion.
Each has it's good parts and bad.
Morrowind:
Good Parts: Long story and multiple side quests, big world without bounderies, lots of items, haven't seen anything that doesn't have a value to it. Enemies aren't leveled so you have to be careful, but neither are items, ancestral tombs, levitate.
Bad Parts: Only thing there is the island... seriously if you up your acrobatics or speed and give yourself waterwalking, you can go from one side of the island to another by moving away from it, can't weild a weapon and cast magic, you can't join the dark brotherhood, no deadra shrines, you need a shield to block and it's a sucky auto thing, alot of attack spells are basically the same.
On the line parts: No compass to tell you where to go, no fast travel (but the boats and silt striders are there for that).
Oblivion:
Good parts: Great graphics, can wield and cast at the same time, blocking is manual and you don't need a shield, you can join the dark brotherhood, Deadra shrines, no questionaire to tell you what they think your class is, but how you play through the beginning, Patrick Stuart as the Emperor and the guy that played the leader of the 3 evil kryptonians from Superman 2 as the leader of the Dawn peoples, the big fight before entering the GREAT GATE, attack spells vary in look and effect now.
Bad Parts: invisible walls, a main story that you can finish before even hitting level 10, the reward armor for beating the main story sucks, the offical mods cost money, less side quests, leveled monsters and items and spells, no levitate spell.
on the line parts: Compass to lead you, fast travel, Oblivion Gates (i liked them, they were my main source of income and magic items and passing time)