I have always dreamed of and liked the looks/design/feeling about BM6000, BG6002, BG 6006 (also the 8000). I think this will be my next project of collecting. Therefore  I wonder: What is the main difference between the Beogram 6002 and the Beogram 6006?

I would welcome every opinion, not only technical. 

Designwise - not much.
Technically - a lot.

Major differences are that the Beogram 6002 are belt-driven where
the Beogram 6006 uses an eddie-current system with extremely precise optical
feedback and no moving parts apart from the platter (and the spindle on which it rests of course).
The 6006 have full datalink where the 6002 only works one way.
The 6006 is processor controlled and has a far more advanced speed control compared to that of the 6002.
The 6002, on the other hand, is built for the MMC1-5 cartridge range where the slightly older 6006 uses the MMC20 range.

Martin

There are 5 decks in this series, though the 6002 and TX are really only similar in looks.

The 6006 and 8000 are to all intents identical except for finish - the 6006 is black - and the cartridge fitted. The 6006 has a 20EN as standard where the 8000 uses a 20CL. Both are tangential tracking and tangential drive turntables. The latter means that the platter is moved using a rather clever induction motor so that there are no belts or gears involved. Very accurate speed control and wow and flutter too low to measure compared to a normal deck.

These decks were replaced by the 8002, which was similar but used the newer cartridges and had a redesigned platter with lower ribs. Otherwise much the same though the later 8000s and the 8002 had a metal tacho disc which is an avantage these days!

At the same time as the introduction of the 8002, the 6002 and TX were wheeled out. These look much the same but are in fact belt drive decks and are much simpler in construction. The 6002 has one way datalink but the TX has none. They are actually rather good sounding decks and not dissimilar to a 4002 in some ways. Better in my view than the later tangentials though the specs would say otherwise. Just shows to listen to the deck and not the specs!!

Technical you mean 6006 is far better than 6002 or.... How about getting hand of these ones. Are they very rare to get a hold to, or...

I want very much a tangential record player, so I tought 4000. 6002 or 6006 maybe 8000 is alternative. But how big difficulties is there to get my hands in one of them. Here in Norway there are very few options to buy used  vintage B & O .

The least valuable is the 6002/TX though they do not seem any more common than most of the others. I would suggest that of the others in the range, the 8002 is the one to have as it has the newer cartridge range and the metal tacho disc. If I wanted a tangential deck and was not bothered by remote control, I would get a 4000 as it is the best made and prettiest!

I would avoid the 6006 as it is rare and not that reliable. The lid assembly on all these decks is more compared to the 4000 series.