If you translated the term form into another language, it could easily be conveyed as a dance.
This is because form and dance are both typically choreographed sequence.
What is the difference between learning a taijiform and learning to dance?
Who said there is a difference, they are the same.
In the old method of learning taiji, the body was trained and techniques were learned sequentially. This resulted in the skill so renown of taiji generations past.
The modern method of teaching is now to learn to dance, to learn a form and then try to use the form as a tool to learn the moves, this approach is nearly the exact opposite to the traditional method. This is because the dance of the original forms was too difficult to learn up front, and because the forms did not form the basis of traditional training. Form based training leaves out so many important things it is not worth the time to list them all, needless to say that learning to practice a dance and learning to practice a form are the same and should not be confused with learning to practice a martial art.
Forms are a type of practice and are designed to refine skills over time, however the skills they refine are introduced one at a time. The traditional methods involve getting the skills and methods down one at a time, when this aspect of training is complete the skills can be strung together in the form properly without error. In many modern and non-traditional schools there is the idea that you learn taijiquan by learning a form, this is not only false, it results in very poor skill levels compared to the traditional method. The problem is that form corrections do not work, breaking a habit is next to impossible, the only solution is to begin training all over again and with a proper method.
Doing things the wrong way over and over, contrary to popular belief, does not lead to learning the right way to do it, rather it is teaching the body to do them wrong. The idea that you practice a form and learn new ways to do the same moves over time is a very poor idea. This is not how the art was mastered in the past, but it is how many people ruin their ability to master the art in modern times. Part of this is because the skills that are found in the forms of taiji are not those that can be seen, they are essentially unseen forces that the student must have introduction to first, before form training begins.
A more traditional approach to learning taijiquan from the form is to take the very first move and learn it by doing it properly many thousands of times. This cannot be done from a book or a video because it requires a transmission that can only be felt, the explanations of what is going on are worthless to the eye, only knowing how they feel will allow the proper approach. This is the only way to unlock a form, because the transmission is the key. Once the first move is learned properly, and this cannot be determined by the student, only then is the student ready to move on to the next part of the form.
When taiji began to be taught to the public instead of just soldiers and martial artists, the method of teaching had to be changed drastically. Cheng-fu found that many people demanded to learn the form up front, however this cannot be done with the proper form, so he simplified it and made it easier. His refinements eventually took into consideration his massive stature, later postures of his taking into account his very large belly which got in the way of some of the more traditional movements. Despite these alteration the form was still too difficult, at one point a friend and student of his modified the form to make it even shorter and more easy, so as to enable the soldiers who were learning the form during the several weeks of training they had at the University where Cheng-fu and others were teaching, to be able to learn the form more easily. The name of the man who came up with the condensed form for the fast paced conveyor-belt setting of the University was Chen Man-Ching, a rather well known enthusiast of taiji.
Now the condensed form of Chen Man-Ching is among the most widely practiced forms, particularly for the conditioning effects it has upon the body. It is a healthy form, however it is not traditional to learn taiji through learning a form and thus the students of Chen Man-Ching that are the most renown, like William CC Chen and TT Liang, sought out and added much more to their own practice and transmissions than was passed to them by Man-Ching himself. Thus many years later many schools are found that employ the condensed form of Man-Ching while still training in a manner closer to the traditional methods than the modern form based training. However there are also groups which employ his form as the foundation of their understanding and do not employ more traditional practices. Also there are those who think that they can learn taiji from books containing forms, among these are Man-Chings own work, however without the transmission of an authentic line the unseen forces of taijiquan cannot be appreciated.
It is my belief that the 108 karanas were the original martial art posture. The training method in which they were mastered in very close to that of traditional posture training in martial arts. There are also many other similarities. What seems apparent to me is that the 108 karanas contain versions of all of the taiji postures and more and that having reviewed this for a few years now it is also apparent that taijiquan appears to be a refined version of a reduced set of karana postures. The karana postures were used for both dance and martial art. One of the frequent notions of Hindu art containing these postures is that they show dancing, even though such dancing frequently involved weapons and the Hindu classics clearly relate dancing to the martial arts. However many so called experts on India from the west have repeatedly failed to note this connection between dance and martial arts.
Many of the previous posts here illustrate martial dances that appear to have spread out across Asia from India over the last 3000 years. They almost all involve variations of the same posture and slow movement for training and fast movement for application. In many cases the costume of the dancer is based on ancient armor and in many cultures there is a connection between warrior and dance, Japan is a good example of this and the influence of vedic tradition in Japan is also rather apparent.
Over time I have come to see that many dances are more martial than are realized, and many martial forms are more dance like than realized. In the end form equals dance and dance is just form and skill does not come from knowing the choreography, it comes from mastering the moves themselves.