Some are varations on what the founder taught, some are varations on varations, some are pre war so become closer to Aikijujitsu, and one particular style usually offends others with its history. best thing to day is look up these style names and see what you think. 1. Iwama Ryu(Saito sensei, birth place of Aikido) 2. Aikikai(Has lots of ofshoots, style taught by founders son and others) 3. ki Aikido( from the mighty Tohei) 4. Tomiki (sport style from Tomiki, very different o tradtional Aikido) 5 Yoshinkan( more closer to aikijujitsu, from Shioda the great) there are plenty more, most are varations on one kind, some are style's of the founders studenst who went there own way with other martial influences.
The best place to get your info has to be STAN PRANIN of the aikidojournal.com he is the leading brain on aiki history check his site you will find everything you need to know, everything he says is repected the world over
Aikiscotsman describes the range very well. Just to elaborate on two: Yoshinkan is at one extreme - very hard style of applied 'jutsu' techniques which have a place in police and military defence training. I am less qualified to talk about the other extreme, which I would describe as 'Ki' aikido, concerned with harnessing the power of the spirit, which uses more circular movements. IMHO it is easier to progress from a hard physical style to one which is more subtle as one gets older and more skilful. Some believe that was the path of the founder of aikido and, now I'm older (50) I can see how it makes sense - if you don't get broken on the way! If you are thinking of starting aikido I have only 2 pieces of advice: 1. Visit dojos you can reach easily and choose the one which offers the best instruction for YOUR aims - whether spiritual, self defence etc. What you want to achieve and whether you enjoy the training or not will not necessarily be the same thing - you may need to choose. You will need to spend a long time training to reap the rewards, hence my emphasis on choosing one close to you. 2. Unless there is a real problem - stick with that style and train long and hard. Don't dip in and out of different styles. ANY style of aikido requires dedication and all will pay huge dividends in the end. One thing aikido should teach anyone is to be their own harshest critic and their own motivator. Avoid like the plague those organisations who offer rapid pregress and easy Black belts - they are there for weak minded souls who have deep pockets and shallow spirits. Have fun!
