Cognitive and cultural embeddedness: combining institutional economics and economic sociology
According to this, pederasty is sexual relations between two males, especially when one of them is a minor. Other definitions, like the one that JSBangs found, differ slightly. But otherwise, I think you answered the question yourself: pedophile refers to the attraction, while pederasty refers to the act itself.
In many cultures, pederast relationships were considered part of the norm, with the relationship between the older man and the adolescent ending once he was considered a grown man. Pederasty is a debatable thing, whether it is ethically sound or not.