This is comparing styles of taijiquan, so within the subdivisions or Chen Taijiquan, the differences taken in context amount to minutia. Differences in appearance can be accounted for by differences in principles, practices, or an intended application or skill being trained by a movement. Principles from general theory are generally uniform, but how to put that principle into practice may differ. For example, rounding the crotch is a shared principle, but there are differences between the subdivisions in how the crotch should be rounded. A strike in one form could be thought of as a take-down in another form, but this variation is in the deep nature of taijiquan forms. The basic body mechanics of any given movement can be used variously as a punch, a take-down, a grapple, a break, and so on.