OT gave a better chance for beginners and if somebody played MM for the first time without playing OT then they would probably have more problems. OT had lots of weapons that it was harder to use some things like arrows because you could run out a lot of times. The enemies in each of these two games were similar in many ways. Actually many of the enemies in OT had been restored in MM with some new animation and added features. The enemies in MM were better and they had more meaning in each area that they were located.
Bosses are an important part to both games.
OT bosses had some of the coolest ideas involved into them. For example Morpha had spectacular graphics. I would just let it grab Link to see the graphics occur. OT bosses were of course strange but they each had a puzzle to them that you had to figure out. Probably the most graphically best boss was of the Spirit Temple Boss.