Lots of info on the Spektrum website but clearly there is a range difference between the different receivers, i.e. Parkflyer, Full Range etc. Also telemetry capabilities.
It looks a bit of a minefield!
Colin
I have always found it very simple.
In terms of range most surface applications are within say 200m. Parflyers, which are small & cannot be seen if they are a long way away, are flown within their limited visual range and full range can fly large models to visual range (which is further as they are bigger) including in congested radio space.
I have often flown with parkfly receivers & never had a range problem over a range that would dwarf any model bating lake.
Telemetry is great if you have the necessary electronics at both ends. If you don't then it is just an expensive receiver.
For model boat use any of them will do perfectly well as long as they are designed to work with your transmitter protocol. How you locate them in the model is the big variable.
Note that none of the above applies to toy type rc systems which normally includes the radio supplied with cheaper rc cars etc which might have very limited range - sometimes around 30metres.
