There's a huge difference between Apple's built in apps and the third party apps doing who knows what background processing/data mining on phone usage. The effects on performance such as battery life is very noticeable.
Android apps are a bit more free, that leads to a lot of apps being good at talking to each other. But the cost is that your sandbox is less sandboxy.
Permissions are a moot point when you're talking about bundled apps because they're already going to be approved for all permissions.