There are more fish and bugs to catch, and the houses, once fully developed, are a lot smaller. There are pro designs as well, which are better than the ones than on Wild World. You can get 10 neighbours instead of 8 on WW, but they are not really that bigger differences...
Youtube Account: http://www.youtube.com/pdwinnall
I do game walkthroughs. Currently I am doing Pokemon HeartGold and Mario and Luigi Bowsers Inside Story
I have completed Professor Layton and the Diabolical Box