Probably been covered before but here goes.
If you pass your test in an artic, you can drive a wagon and drag.
If you pass in a wagon and drag, can you drive an artic?
Sorry if i am being thick
yes and yes.
tofer:
yes and yes.
Agreed.
Is a wagon in drag. one of them with a giant black wig and lipstick. 
SWEDISH BLUE:
Probably been covered before but here goes.If you pass your test in an artic, you can drive a wagon and drag.
If you pass in a wagon and drag, can you drive an artic?
Sorry if i am being thick
Answer yes to both as they are both C+E.
Advice - train in the type of vehicle that you are likely to be driving on your first C+E job which in well over 90% of cases will be ARTIC and not W&D.
Both types act differently on the road and more so when reversing.
Back to your original query -
Where the confusion can come in is where the different types are referred to as ‘classes’ as this was the old UK HGV terminology which referred to a different system of sorting them out.
RIGID with 2 axles Class 3 HGV - now C
RIGID with more than 2 axles Class 2 HGV - now C
ARTIC Class 1 HGV - now C+E
Some of the old Class 2 & 3 HGV had W&D entitlement but not ARTIC unless they took the HGV Class 1 test
The EU regs which, I think came in 1997, changed everything into different sets which made any type of rigid (an artic unit is a rigid) that had a trailer attached into a C+E - the C being the rigid bit and the E being the trailer.
Yes, they are both the same thing, a heavy vehicle (Class C) and a trailer (Class E).