A tablet (pian) may contain fillers such as silicate etc. much like common pharmaceutical tablets do.
These should not affect the formula as they are fairly inert.
If the herbs are different to the original formula, this could be one of a few things, either:
- Some of the herbs in the original formula are now restricted or illegal for use in that country,
- One or more of the herbs has been replaced with a less toxic genus or deleted for its toxicity,
- The interpretation of the herbal formula has come from another source/text which includes a slightly different composition.
- The formula is a variation aimed at a particular health condition which has been stated on the label,
- The formula is a different one altogether, and you have confused the Chinese pin yin names such as the following example:
Si Ni San or Counterflow Cold Powder and Si Ni Tang or Counterflow Cold Decoction look almost identical in Pin Yin and English names however they are completely different and opposing formulas, one of which works through the actions of Chai Hu (Bupleurum), Zhi Shi (Citrus Aurantii Immaturus), Bai Shao (White Peony Root) & Zhi Gan Cao (Honey Fried Licorice Root) to move constrained Liver Qi and free up the flow to warm the limbs.
Si Ni Tang however uses the actions of Fu Zi (Aconite, now illegal in many countries), Gan Jiang (Dried Ginger Root) and Zhi Gan Cao (Honey Fried Licorice Root) to warm the channels in the case of Yang collapse and restore warmth to the limbs.
So there are many factors which might affect the ingredients list however you are correct - alteration of the constituent herbs can change the formula quite drastically.
Please note however that some herbs are considered acceptable substitutes for others and do not change the herbal formula's ability to alter disease state except for the strength. One notable example is when Ren Shen (Panax Ginseng) is unavailable or too expensive, often Dang Shen is used instead (Codonopsis Piluosa) as this has a similar effect, only the strength is diminished in comparison with Ginseng.