RE: What is 'It'?
You are going to get a lot of responses to you question and they are going
to vary a lot.  But having come into the VW community (alternate spelling:
Cult) late in life I've listened to a lot of VW people talk about their
vehicles in many different terms.  I've arrived at a couple of labels that
seem to be appropriate.  For the early VW Transporters, they are Buses.
They have earned that distinct and venerable title.  If differentiating
within various versions from over the years 'Splittie' or 'Bay' pins them
down a little tighter as to the vintage.  Then adding 'Camper' or Westy or
Westfalia further defines things.  For the Vanagon I've adopted the generic
'Van', not Bus.  I think Bus should be reserved for the pre Vanagon VW
Transporters. BTW, Transporter is the more official VW label for the Buses,
Vanagons, Eurovans, etc.  As for the Eurovans they are just that, Eurovan or
Eurovan Camper when I talk about them.
And then there is the often confused designations of 'Transporter' and
'Type'.  For VW all Buses and their descendent's are 'Type 2' or
Transporters.  But within  the Transporter line there are T2s ( 'Transporter
2's' , Buses), T3s (Vanagons), T4s (Eurovans) and now the T5.  And to
further confuse everything the Vanagon name was only used in North America,
VW put other labels on the Transporter 3 in other parts of the world.  And
then in the UK, what we call the Vanagon is often referred to as a T25 after
the '25' in the VIN number.
Is their a 'Right Way' to refer to our Vanagons? I don't think so except
maybe as 'My Money Pit'.