I just love how people talk of homosexual sodomy as though it isn’t the same as when their girlfriends give them blowjobs or they have anal intercourse with their female partners.
There is no sex act homosexuals engage in which is exclusive to homosexuals.
There. I feel better. 
IANAChristian. Having said that, let me state why I think some people make the distinction. Some Christians believe that homosexuality is a sin. This would make whatever sex acts homosexuals practice, a sin by extension. However, somewhere in the Bible, the Bible states that “The marriage bed cannot be defiled”. IOW, a (heterosexual, one would suppose) married couple can practice sodomy all they want. Or whips and chain, or whatever turns them on, so long as it stays between husband and wife. If non-married heterosexuals engage in any sex act, it falls under the heading of fornication (or adultery, if one of the participants is married), which is a sin. If gay men do it, it’s homosexual sodomy, also, some say, a sin.
Homosexual sodomy (unless one conflates homosexuality with any number of sexual acts involving any number of partners unable to consent) involves two consenting adults of the same sex. This phrase is used to distinguish between heterosexual sodomy and homosexual, and depending on the context and company can be meant to drive utter disgust into the heart/stomachs of one’s audience.
Someone will probably be along shortly with a more nuanced answer to your question, but that’s the bare bones of it;)
Well, I see that that’s done. Next?
According to the laws of various states - which were declared unconstitutional by the latest SCOTUS ruling - there is a difference. Some states only defined acts between homosexuals, while others extended it to heterosexuals too, including oral sex rather than just anal sex (as some people define sodomy). Still others, IIRC, included things like bestiality as part of their sodomy definition. So yes, according to certain states at least, sodomy is not necessarily oral sex between heterosexuals.
I think norinew and iampunha have answered the OP’s substantive question quite well, but can’t help chiming in with a classic nitpick:
Contemplate the soixante-neuf. There are, in fact, two acts which may be engaged in only by same-sex couples: mutual fellatio, and mutual cunnilingus – just as one of each, simultaneously or in succession, requires an opposite-sex couple.
Color me curious (but not yellow)… what’s the French phrase mean there, Poly?
WTF is “homosexual” sodomy? Isn’t “sodomy” regardless of gender of participants
You’re obviously doing it wrong. 
PSSST! You, up there…
sixty-nine
Hey, ok!
Oh. Never mind.
Anyway, that’s no fun. I was going to make him guess It’s a number. And it’s greater than 68…
I just wanted to add a little class to a discussion of sexual practices!
I also hate it when people talk about “chicken fajitas.” There is no such thing. Fajitas are beef by definition.
It is precisely because sodomy does not specify the homo/heterosexual nature of the act that permits one to non-redundantly specify it as “homosexual.”
Furthermore, not only is sodomy regardless of the sex of its participants, so is homosexual sodomy. The only caveat is that both members must be of the same sex.
I suppose I’ll have to take your word for that. Still, “chicken fajitas” can’t possibly be as abominable a term as “chicken scampi.” I swear to God, the people who run the chain of restaurants that the citizens of Orange County, California routinely vote “best Italian Restaurant” actually believe that chicken can be shrimp.
What’s next? Wheat *pilaf/i]?
And what’s with people who vote the Olive Garden the best Italian Restaurant? That happens in Houston, too. “Ooooh, they have the best breadsticks!!” (so these people say)
And do you know what they do with those breadsticks!!!
Talk about sodomy…
My ignorance has not been fought today… I still don’t know what Poly said. I thinkI’m gonna cry. 
Soixante-neuf is sixty-nine. Beagle already pointed this out, but you may not have noticed that his comment
was referring to you. It’s one of those things where if you already know the French, it’s obvious that he’s pointing to your post, but if you don’t, it’s not.
[Reverend Lovejoy]
Have you ever read this thing? Technically, we’re not allowed to go to the bathroom!
[/Reverend Lovejoy]
I’m sure this has been discussed in the past, but perhaps Poly or someone could enlighten me:
I thought that the sin of the denizens of Sodom was described somewhat ambiguously in the Bible, such that it was more likely “treating their neighbours disrespectfully” rather than “putting their knobs in each other’s arses”.
And just what did they get up to in Gomorrah, anyway?