Pederasty is the (usually) consentual homosexual act between two males, one of them adolescent by the origin of the term, but not necessarily in the modern days (e.g pederasty was illegal under Soviet occupation as a mere sexual act between two consenting males).
p***philia, however, is a sexual act between an adult and a child - leaving legal room of debate (e.g 17yr old with a 26yr old partner), but socially perceived in Western cultures of the Northern hemisphere (and those with remarkable influence by it) as a sexual act of a willing adult with a child unable to purport will. This can, in turn, be broken down into other lengths (e.g a wealthy 50yr old with a 17yr old might be construed as a gold-digger relationship vs a 30yr old molesting a 16yr old vs a 30yr old molesting a 12yr old). Ages of consent play a huge legal role as well, as in several European countries the age of consent is often 14 or 16, with no legislation marking the maximum age difference in regards to age of consent.
The hypersexualization of children is eery mostly due to the fact that if we take the Roman Empire as an example (which is ipso facto incorrect, the Hellenic period in Ancient Greece was much more into sexual relationships with children, i.e young males), the tables have seriously turned. The modern sexualization of children acts as objectifying young females, while victimizing the paedophiles. The sexual need of the paedophile is seen as a "disease", an utter pang, and support is being "given" by the society. Take Scandinavian countries, where you can even find paedophiliac political parties - or those child sex dolls, or anything else.
This agenda is horrific and breaks the last taboo - remember, even the arch enemy of Gengis Khan refused to kill him as a child, since he was less than a sword tall.
In the entertainment industry, in popular culture, in fiction, everywhere around us, we see the sexualization of young girls, and that makes one ask many serious questions.