Two classes advertised under the same name can involve entirely different activities, one held and slow, the other continuous and demanding. The variation is a product of how the modern practice was assembled rather than of teachers deviating from a standard.
The postural tradition is more recent than assumed
The philosophical texts most often cited concern ethical conduct, breath and meditation, and describe very few physical postures.
The large repertoire of poses recognised today was consolidated relatively recently, drawing on indigenous physical culture alongside gymnastic and callisthenic systems circulating at the time.
Because that consolidation happened in several places at once, it produced parallel systems rather than a single lineage with branches.
Sequencing reflects the aim of the system
Some systems use a fixed series performed in the same order every session, which allows progress to be measured against a constant and builds familiarity.
Others treat sequencing as something a teacher constructs for the group in front of them, which prioritises adaptation over comparability.
Neither approach is a modification of the other. They encode different assumptions about whether the practice or the practitioner should be the fixed element.
Pace determines what the session actually trains
Continuous flowing styles link movement to breath with minimal pause, which sustains an elevated heart rate and makes the session cardiovascular as much as anything else.
Styles built on long holds do the opposite, using passive positions maintained for minutes to load connective tissue and to give attention somewhere to settle.
The physical demands of these two are so different that comparing them as versions of one activity obscures more than it clarifies.
Heat and props are structural choices
Some schools practise in heated rooms, which increases tissue extensibility temporarily and raises cardiovascular strain and fluid loss substantially.
Others rely on blocks, straps and walls to bring positions within reach, treating alignment as the priority and accepting whatever range the practitioner has.
These are not accessories added to a common method. They follow from what each school believes the posture is meant to achieve.
Why the label alone tells you little
Regulation of teaching qualifications is limited in most countries, and the same style name can be used by schools with different training requirements.
The practical questions concern pace, temperature, holds and whether modification is offered, none of which are conveyed by the name on the timetable.
Anyone with a joint condition, high blood pressure, glaucoma or a recent injury should establish suitability with a clinician, since several common practices are contraindicated.