Mizter T wrote:

You're probably getting confused with the *non visitor* (i.e. regular)
Oyster cards, which IIRC initially came without pre-loaded credit but
that later changed, and were available from standalone vending machines
in a few Tube stations - this arrangement doesn't exist any more as
regular Oyster cards can now be obtained from the larger sized Tube TVMs.

Other than the graphic and initial loading, is there any functional difference
between a regular and visitor Oyster card?