RescueTime logs by app/website. In PunchT, you log manually.

RescueTime way it's easier, but not that accurate. For example I use StackOverflow for both work and leisure. RescueTime both uses logs as same. By logging manually, I can mark the difference between those activities.

That's helpful -- a helpful explanation, I mean, as well as a potentially helpful tool. It'd be great if you could say more stuff like this on your home page. I tend not to sign up without a lot more information.

Presumably because RescueTime does a lot of the grunt work for you by monitoring your computer with an agent, and this won't.