From a psychological perspective, rather than a legal one, a paedophile who is someone who is sexually attracted to pre-pubescent children. Therefore anyone (irrespective of their age) who is attracted to 'fully developed' teenagers (even though those teenagers might be only, say, 14 years old), is not strictly a paedophile, even though the media would probably use that label.
Chris
PS: I always think that the use of the word 'paedophile', to describe someone who lusts after children, is a mis-use of the English language. 'Phile' relates to 'love', not 'lust'. (e.g. a 'bibliophile' loves books; he doesn't seek to abuse them). If we used language correctly, paedophile' would be used to describe someone who genuinely loves children (e.g. Mother Theresa of Calcutta or Princess Diana). We already have a word for those who sexually abuse children; it's 'paedarast'.