Malfuf: DkkTkkTk Serto: D kT kTk
Beledi: D D kkT D kkT kk Basic Beledi: D D T D T (aka Masmoudi Saghir)

It's the same kind of difference. The Serto is the same rhythm as the Malfuf (or Leff)

Here's a brain twister for you:
I play with a lot of Greek bands for weddings and parties and when I first began doing it a couple of years ago they asked me to play a Ciftitelli and I played what I know as a Ciftitelli and they all looked at me and asked :"What is that?" Then they tapped out the beat that they know as Ciftitelli and it went like this:
D T kk T D kk T kk
I said: "That's a Maqsum" and they said: "No! That is a Ciftitelli!"
So I asked around to a lot of other Greek musicians and sure enough, a Maqsum is what the Greeks call a Ciftitelli.

Then I really understood the real lesson to be learned as you study ethnic rhythms. There is no universal standard. Every area has its own variations and names................. and they'll all argue that theirs is the "right way".

Don't get me wrong any of you. I'm not being argumentative here (sometimes it comes across that way on-line because we all write the way we talk and without the inflections it can seem that way). I am agreeing that there are differences in perceptions of rhythms and it is not only regional to places that are indigenous but also here in America.
Johannes,
Did you learn Serto in the SCA? (That's where I originally learned ME drumming, but I've been a drummer all of my life). Once I got involved with actual Arabic and Balkan musicians, a lot of the SCA myths about correct rhythms faded away.I realized that there were similarities and very specific regional and personal interpretations of the rhythms by the "real" masters.
I was originally taught Serto from SCA drummers this way:
D kT kTk D kS kTk (this is an SCA specific notation)
They played it very slow and it had a drifty and dreamy feel to it. The way that the Greek bands play it, it's played at the same tempo as malfuf.
I've played with a number of Greek musicians and it is always played at the tempo of a malfuf.

We tend to project "Western" sentiments on all of the rhythms and for that matter all of the music that is categorized as "world". It is not as universally "formal" as European conservatory music is (though in some places it may be). Much of what we learn especially for our goblet drums, is from an ethnic "folk" perspective. I hate to shatter any illusions, but our goblet drums (derbekkes, dombeks, darbukas) are not "court instruments", they are folk instruments. In the last century, the goblet drum has become the primary percussion instrument because of belly dance. There are now very formal ways of playing it that were not necessarily the case in the past. It's rather like the difference between a fiddler and a concert violinist.

The names of these rhythms and how they are played vary greatly from place to place. The answer for the serious student is: study them all.
It'll be like gathering folk tales. Each new thing you learn will give you a better understanding of the music and the culture, and they'll all be a little bit different. There's a lot to learn and you'll never get it all. There will always be something new to learn and that's what makes it interesting. This doesn't mean that you don't study technique and proper form, but even with that, there will be subtle variations. Study with a master (a real master that is an accepted master) and learn as much as you can about their technique and how they play and call the rhythms. Then expand your scope. Or if you wish, you can stay within a certain genre if that's what interests you. Eventually you will develop your own techniques and style that is correct, but unique to you. (And then you'll have all sorts of educated disciples in another form telling their friends that you're doing everything wrong.) But you have developed. So long as you stay true to certain basic principles your subtle ornamentation and variations will not only be acceptable, but welcomed.

I have many SCA drummer friends and I love playing with them, and of course we will argue about certain things but the SCA has changed a lot and there are now many really good drummers there that have trained with masters and there is now great variety. Only playing in the SCA will make you stagnate though. Get out there and learn and play with others. Hang out in Arabic and Turkish and Armenian and Greek clubs and listen. You'll learn a lot. Then bring it back to the SCA and we will all learn.