Is there a semantic difference between "pedophile" and "pederast"?

Solution 1:

Pederasty is defined by M-W as:

Anal intercourse, especially with a boy as the passive partner

Whereas pedophilia can refer to any kind of sexual attraction to children, including attraction which is never consummated, or which doesn't result in intercourse.

Solution 2:

My understanding is that a paedophile is attracted to pre-pubescent children; there is another little-used term to describe one who is attracted to post-pubertal children, but it escapes me. [Edit: add ephebophilia to JSBang's hebephilia — I suppose we ought to add in teleiophilia and gerontophilia to our list of chronophilic terms.]

A pederast is one who has a relationship with a [usually] adolescent boy.

The differences are many, and it is a mistake to think these are synonyms. For one, historically a pederast would have a far more involved relationship with the child; secondly, pederasts are concerned with post-pubertal children; and finally, the relationship is (AFAIK) exclusively homosexual.

From Wikipedia's entry on pederasty