Writing this from my Facebook account.
Assuming there is still interest in the thread, I'll weigh in and see if I can help.
I have done a few MAs, but I'd like to consider myself fairly well read about them :I so here goes.
I'll split some common ones into a bunch of categories.
*grappling based*
JUDO. Judo has a heavy focus on clinch grappling and throws, with ground grappling ranging from excellent to poor. Judo throws can be split into leg throws eg osotogari, hip throws eg ogoshi, shoulder throws eg moroteseoinage, hand throws eg morotegari and sacrifice throws eg tawaragaeshi, their ground game is heavy on pinning, and submissions from the top, though many have good triangles and guillotines. Judoka are clinch grapplers par excellence, only Sambo fighters and GR Wrestlers coming close. Dirty boxing and ground-n-pound come naturally to a good Judoka, and they are often strong and durable like wrestlers with with incredible grip strength, basically Judo is submission wrestling, quite similar to CACC.
BJJ. Brazilian Jujitsu is closely related to Judo, but sacrifices the clinch for the ground, BJJ fighters are better than anyone when it comes to fighting off their backs, with many unusual submissions, sweeps and guard positions from there, they tend to be more willing than Judoka to try new things, with many being good wrestlers, and in a street situation will still be able to takedown or throw most non grapplers, BJJ fighters often have great cardio, but less strength and endurance, and some have found themselves overpowered, and tend to adapt to strikes worse than any other grappler.
SAMBO. Sambo is a blend of Judo and Russian wrestling, they are very similar to Judoka except that have very little remaining influence from Jujutsu, but have a variety of wrestling attacks and a pragmatic approach to techniques, they ban chokes but allow leglocks. Combat Sambo adds Russian Boxing and kicks to basic Sambo. Some Sambo styles allow chokes. Military Sambo is Combat Sambo combined with military H2H.
WRESTLING. There are 2 main types of wrestling, folk/freestyle and Greco-Roman, neither allow submissions, and both tend to be very poor off their backs. Folk is heavily takedown based, doubles, singles and the odd high crotch or ankle pick, they have many powerful suplexes and slams though, and have good top control, and GnP is the most natural skill set to develop. GR wrestlers, otoh, cannot touch below the waist, but are amazing with hooks, from the back and from a collar tie, it's a more esoteric style, and less popular, with many odd rules, but good for clinch boxing. There are wrestlers who are good grapplers, such as those from CACC or are belted in BJJ.
*Striking based*
BOXING. Boxing is easy to underrate, while modern boxing is fully focused on ring fighting, more traditional attitudes are more applicable to actual fighting, but boxers, like wrestlers, realise the importance of strength and conditioning, and as such are almost always incredibly strong and fit. There are many styles and attitudes to boxing, the American, Cuban, Russian and British boxing. both modern and antique, vary quite a lot, British Bare-knuckle, with its high stances, Karate like hand position, and preference for straight punches and forearm blocks looks almost like a different art than Modern 1-2-3 combination boxing, frenzied infighters or the Eastern Bloc's predilection for casting hooks, power punching and punch-and-clutch.
KARATE. aka teh Krotty. Karate can mainly be split into three types, traditional, knockdown, and modern. Traditional varies from tough old Gojuryu, KUGB or JKA Shotokan to kids in pyjamas, there are 3 main 'lines' Nahate Tomarite and Shurite, Nahate is stuff like Goju, Shuri is Shoto and Shito, as well as stuff like Wado, which is pretty much half Karate and half Jujutsu, and Tomari influences both. all three come from different cities in Okinawa, and have influences from Indochinese kickboxing, Quan Fa aka 'kung fu' and martial arts from south east Asia. Naha stuff tends to be more mobile, with high stances and circular techniques, while Shuri stuff is more simple and direct, moving in and out like fencers, and favouring basic moves like front kicks and straight punches. Modern stances look very little their predecessors, Karate actually being quite similar to bareknuckle boxing 100 years ago or so. Karate was often taught along side Tegumi, which is Okinawan wrestling, and Kobudo, which focussed on weapons.
Knockdown Karate is mostly descended from Kyokushin, a blend of Gojuryu and Shotokanryu and is full contact, with no gloves, but knockdown competitions ban head punching, KK guys have incredible durability, possibly more even than Nak Muays do, and combine body punching and a massive array of kicks, having powerful low kicks, as well as using unusual ones like hook and axe kicks, plus I have never seen more versatile headkickers in my life, able to land them from body punching range. They often struggle tremendously with boxers, and people punching them in them head :3, but offshoots sometimes allow headshots with mma gloves, or light mitts, and plenty spar with head shots.
Point Karate sucks buttballs. Well, to be fair, some point karateka are amazing athletes, but on the whole they are awful, and it can actually make a useless person even worse at fighting :I
TAEKWONDO. ITF TKD is basically traditional Krotty, with a bunch of extra kicks in it. Tangsoodo or TSD, More properly Dangsudo, is even more like Karate, WTF TKD is that mental bouncy-bouncy kick slappery in the olympics, TKD can be practical, with them being very hard kickers, though Muay Thai and Knockdown Karate both have stronger round kicks, and Sanda combining TKDs side and back kicks with kickboxing and the ability to actually fight. Overall though they have a pretty bad reputation and not entirely undeservedly. They also tend to cry if you punch them, or if you ask them to fight when they don't get to wear body armour.
KICKBOXING. The most common KB is Muay Thai, which consists of basic punches, push kicks, round kicks, knees and elbows, and unrivaled clinch striking, they tend to fight by trading single kicks and knees at long range then kneeing the assjam out of each other in the clinch, a good MA for lanky people with long legs, their boxing tends to be poor, and they often struggle in punching range, when they are too close to kick but too far to grab, they also favour a grinding war of attrition, though this holds less outside of Thailand. There are other Indochinese styles similar to MT, like Bando and Lerdrit. Some allowing headbutts or have other minor differences.
Japanese Kickboxing is a blend of MT, Karate and Boxing, on average being better punchers, more varied kickers but worse in the clinch than MT fighters or 'Nak Muay' as it is said in Thai.
Dutch KB, like Japanese KB, is a mix of Kyokushin, MT and boxing, they are much better boxers, and prefer to fight at mid range, throwing punching combinations finished with low kicks, many see to be essentially boxers who can low kick.
Savate in it's modern form has western boxing added to a very odd style of footwork and kicking, they wear shoes, and favour quick, flicking kicks, not power round kicks, but hook and crescent kicks, they also love stamping the shin and knee, Savate is a tricksy style, with pretty solid hands.
American KB is basically traditional Karate, TKD and boxing, they're good boxers but middling kickers, often not allowing low kicks and using snapping side kicks and more bladed stances, good fighters but they can die to leg kicks. Often only semi-contact, blech.
Sanda, or Sanshou, is Chinese KB, descended from a variety of schools of Quanfa, it's a great style, often have good hands, throwing from the clinch is allowed, and prefer the side kick to the round or push kicks, quite similar to a blend of WTF TKD and Greco-Roman wrestling.
Hope that was informative, if anyone has any queries or wants to know more just let me know. I can go over these in more depth or give an outline of other stuff.