600EX-RT questions

1. Is the built in wireless functionality the same as ST-E3-RT?
2. When using the flash as an on-camera master, can I make adjustments to off-camera 600EX slaves, either in TTL or manual, via the camera's menu?

Thanks

Number 1.
The ST-E3 menu operates the same as a 600 EX-RT. Radio is controlled the same also.
Number 2.
Why would you then want to control functions in camera menu?
What makes this system great is that both the flash and transmitter menus are the same, streamlined system. Very simple and consistency.

I respond too, since the reply you got is either wrong or incomplete.

1. No. The 600 EX-RT features both optical and radio wireless control. The ST-E3-RT is radio only.

2. Yes, but if you don't have a camera that's introduced in 2012, you can't access all functions in the 600 EX-RT from the camera's menu system. If your camera is older, like a 7D, you can access everything you'd also find in a 580 EX II. Thus you can set up the optical wireless system, but not a radio controlled one. You'll need a 1DX, 5D Mark III or a 650D to be able to set everything via the camera's menu system.

On the flash itself you can still set these items not supported by the camera's menu system. But even there, you can't use the Group mode, a mode available only when using radio control and when the master is used in conjunction with a 2012 camera (one of the three listed above).

True, there are even more limitations for older cameras. OP's signature line indicates a 5D Mark II is at hand. Then the lack of group mode is probably the most important limitation. Those who have tested claim that the loss of sync speed isn't always true.