Your letters, but scrambled.
 

I've only run into two cases that I can remember off the top of my head where two national greek organizations have the same letters but scrambled.

1) Kappa Sigma Fraternity and Sigma Kappa Sorority (not related as far as I can tell)
2) Alpha Phi Omega Serv. Fraternity and Omega Phi Alpha Serv. Sorority (OPA was founded with the help of APO brothers, but no legal tie)

Are there any other examples that people can thing of? I know this is something that Tri-Delta and Tri-Sigma don't have to deal with...

Heh, this thread reminds me of the time one of my sisters bought a Kappa Sigma decal for her little. They're backwards for the inside window of your car. Whoops.

I don't think this is exactly what you're looking for, but there's all the groups with just one letter different:

1. Phi Kappa Sigma / Kappa Sigma (this actually confused me for a while freshman year, and I walked into the Phi Kap house thinking it was the Kappa Sig house. Stupid freshmen)

2. Phi Kappa Psi / Phi Kappa Sigma

3. Pi Kappa Phi / Pi Beta Phi (even more confusing because on my campus, we refer to both groups as Pi Phi [I've heard a bunch of different stories as to why, but really not sure how that came about] which eventually lead to the fraternity being known as "Guy Phi")

4. Pi Kap / Phi Kap

5. Pi Kappa Phi / Pi Kappa Alpha

I'm sure there are some others. I think the conclusion we can draw is that the letters Pi, Kappa and Phi were very popular at some point.

ETA: Also, Chi Omega / Alpha Chi Omega

We had the same issue, as at my alma mater we also had both groups. We ended up calling Pi Kappa Phi either "Pi Kaps" or "Pi Phi's for Guys". I've never heard "Guy Phi" before! :)

Or Phi Sigma Kappa and Phi Kappa Sigma.

At my school we called Phi Sigma Kappa "Phi Sig". Thank God we didn't have Phi Sigma Sigma or that could've been confusing.

On my campus, there's Delta Phi and Delta Psi, also known as St. Elmo's and St. Anthony's (or St. E's and St. A's), with similar reputations and right next door to each other. They pretty much blended into one group in my mind.

My boyfriend and I were just debating this last weekend. He referred to them as the guy Pi Phis. I asked him if he was referring to Pi Kapps. He was convinced that that nickname was incorrect because according to him "no one uses the middle letter in the nickname". I guess him being a Phi Psi, and he knows many Pi Phis, I could see where he gets that. But then I reminded him of Gamma Phi, Alpha Chi, Alpha Gam, Alpha Sigs, Delta Sigs, Phi Delts, Lambda Chi...just to name a few... lol

Alpha Phi Delta and Alpha Delta Phi which are both fraternities.

Until GC, I had never heard of Pi Kappa Phi being referred to as Pi Phi - on my campus, they are the Pi Kaps.

Funny story - when I was a baby colony member, we decided to do posters for all the fraternities and the one other sorority on my campus for Valentines Day. I had been greek less than a month (we colonized on 1/15/04)...and honestly, I hadnt learned all the letters yet. I was on the committee to make "AXiD <3 (letters of org)" posters.

Imagine my horror when I got to the school to hang up the posters on the suite doors only to realize I had drawn Phi Kappa Pi. I was mortified....and ran to walmart to get supplies to make a correct poster.

On that same note - it took me forever to learn that a Gamma does not look like a 7.

We do at my alma mater. Phi Sigma Sigma was first so Phi Sigma Kappa is simply known as "Kappa". Come to think of it, people rarely ever use their whole name, but there chapter is so small compared to the others it's very easy to "forget" them altogeher. We used to have Phi Kappa Sigma, but from what I understand they simply went by Skulls. At one point we also had Kappa Sigma, but I don't know when they were on campus or if they ever were all on campus at the same time.

We have Pi Kappa Phi, "Pi Kapp" and Pi Kappa Alpha, "Pike".

Could be useful in Risk Management. If a brother or sister draws a Gamma as a 7 they've had enough to drink.

So far
 

So right now the list is
Kappa Sigma(NIC)/Sigma Kappa(NPC)
Alpha Phi Omega (Service)/Omega Phi Alpha(Service) (Historical tie)
Phi Kappa Sigma(NIC)/Phi Sigma Kappa (NIC)
Alpha Delta Phi (NIC)/Alpha Phi Delta (NIC)

isn't there Alpha Gamma Delta and Alpha Delta Gamma? Did I make that up?

Nope.

Add Alpha Gamma Delta (NPC)/Alpha Delta Gamma(NIC) to the list.

And also
Theta Phi Alpha(NPC)/Phi Theta Alpha(Honorary History)/Theta Alpha Phi(Honorary Theater)

At my alma mater, we had:

Phi Sigma Kappa and Phi Kappa Sigma
Kappa Sigma and Sigma Kappa

and a few groups with one-letter differences.

Things could, and did, get confusing. We had the occasional PNM going through NPC recruitment, who would accidentally say that she was preffing Kappa Sigma. :p