There is no difference in main ingredients between soap and soap powder. They are all long-chain sodium fatty acids, and the "advanced" in organic chemistry is long chain, not high quality or poor quality.

However, in order to set the soap, a certain amount of rosin acid needs to be added as the setting agent. In addition, in order to enhance the washing effect, sodium silicate and other ingredients should be added. Generally, rosin acid is not added to soap powder, but in order to resist hard water and improve washing effect, some metal complexing agents, such as pentasodium and soda ash, can be added.

So, in essence, there is no difference!