pals

I mean there's of course tiers where some are more similar than others in that sense but yah sometimes they do joined sisterhood kinda events

I'd say theta and phi Mu remind me a lot of each other
Same with pi phi and gamma phi
Axo is like a lesser version of aopi maybe for an example of ones in different tiers

The ones that seem to like get along well and/or have a lot of sisterhood evens together are
Like op said:
Pi phi and gamma phi,
AOPi and AXO
Also:
DG and AGD
Sk and tri Delt

Basically the ones who tend to pref a lot of the same girls tend to get along well. Also I wouldn't say that theta and phi mu are very similar. I know a ton of thetas and apparently a lot of them don't like phi mu. Idk why though haha

I'd say maybe ...

Pi Phi and Gamma Phi (and DZ?)
Zeta and KD
ADPi and Phi Mu
Theta and Kappa
AGD and DG
SK and DDD
AXO and AOPi seems weird, but they are both kind of Christian-y
Chi O and DZ?

SDT kind of does their own thing, and DPhiE is tbd