Greater London differs according to definition. Some say it is only the London postcodes: N, S, W, E, WC, EC etc. Others say it's the confines of the London Orbital or even the M25.
Do you mean is Greater London in the south east of England (yes obviously) or does the south east of England include a place called Greater London - the answer to that also surely is “yes”
I don't believe I've ever seen a road sign indicating the way to "Greater" London, though. Plenty for "Central" London as the motorways draw closer to the capital, and all round the London Orbital.
Ichkeria up until recently I thought same but if you google what are the south east counties London is not included. Furthermore google maps exclude Greater London in the “south east” highlighted areas
it depends who you ask. Geographically, yes, that's where it is. But a guide book, for instance, may well list them as separate. I don't know of any legal definition of the south-east.
This considers some of the options (and also see the comments at the end)
Greater London may well be separated from the rest of the South-East on maps and in road atlases etc because it is usually shown in greater detail ie in a larger scale.
I live in Greater London and I live in a county (Middlesex). My town used to be in Surrey but the boundaries changed. Greater London has quite an interesting history as far a boundary changes are concerned. It depends in what capacity you are talking about.