As far as I know from technical point of views, not much differences. The ONLY difference is way the Radios work, the 35 mHz is subject to interference from other equipment operating on the same frequency. With the 2.4gHz the Transmitter and the Receiver bind to each other and the receiver will only accept commands from the transmitter it is bound too.
In practical terms they both do the same thing, however 2.4GHz have benefit from
1. For the lack of interference
2. It has a much shorter aerial