In my defence, I was coming at it etymologically, where (according to the OED), a perambulator is 'A person who walks or travels through or about a place' (hence 'walker') OR 'A carriage for a baby or young child, which may be pushed along by a person on foot. Now usually shortened to pram [...] a cradle mounted on four wheels'.
My understanding was that a pram is used for a younger child, they are laid flat. A pushchair/buggy for an older child, they sit. Language is often used incorrectly however.
