What are the key differences between the Canon Speedlite 580EX II and the Canon Speedlite 600EX-RT?

The key differences between the Canon Speedlite 580EX II and the Canon Speedlite 600EX-RT are that the 600EX-RT has built-in radio transmission for wireless flash control, while the 580EX II relies on optical transmission. Additionally, the 600EX-RT has a higher maximum guide number and faster recycling time compared to the 580EX II.