LHR SIDs
Apologies - a question from the unwashed here ....
I have a very basic understanding of SIDs. i.e. Seaford, Compton, Brookmans, Dover departures etc. But can anyone tell me what the difference is between say a Dover 2G (if there is such a SID) and a 5G departure ?
Is it simply down to aircraft performance - climb rates, noise abatement, routing ? I read the ais SID plates but have yet to determine the answer - any information would be most welcome.