I did some looking, and it looks like both terms can be used to imply what they have been translated to imply, but that their meaning is likely somewhat different.

"Malakos," translated as effeminate, also means soft, and was the word used when speaking about a rich man in the verse which says it is easier for a camel to pass through the eye of a needle than a rich man to enter heaven, but it was also in common usage as a sexually wanton person and an effeminate male prostitute, so the thinking is that it COULD have been used to imply the "catcher" in a homosexual relationship, although it is more likely by far that it is making reference to the same rich people referenced in the "eye of a needle" passage.

"Arenokoitai," translated as homosexual, can refer to being the active partner in intercourse, male prostitution, or raping little boys (well, pederasty, since the Greeks didn't really call it rape).  This one has a stronger case for being an outright reference to homosexuality, but there is still enough ambiguity that it could simply be referring to general sexual wantonness, or it could even be referring to statutory same-gender rape.