Can caustic soda and soda ash with sunflower oil and coconut oil be use for liquid soap?

i Need a help can i use caustic soda soda ash and good oil to make liquid soap instead of potash?

corporatelab is right. One is chemically produced, the other from ash. Sodium hydroxide is more predictable in soap making. Using either one to make liquid soap won't work unless you don't mind washing with a disgusting looking liquid that resemble drool. Do you want to make liquid soap for body wash or dish soap?

In my (limited) experience, I know that caustic soda (sodium hydroxide) and caustic potash (potassium hydroxide) are commonly referred to with the same moniker: lye. Potassium and sodium in general react very similarly, and their products in general are also similar. As an example KCl and NaCl (potassium chloride and sodium chloride). NaCl by itself is common table salt. Add the two together and you have what is sometimes referred to as "lite salt"; you get less sodium and more potassium in your diet (desireable) and they taste and look similar enough that it is considered a salt substitute.

So far as I know, KOH and NaOH both can be used to make soap with oils. And both require pretty much the same handling and are about equally dangerous.

definitions need to be clear here - it is easy to get confused with some of these words.

caustic soda is sodium hydroxide is NaOH - also called lye.

soda ash is sodium carbonate is Na2CO3, commonly called "washing soda".

caustic potash is potassium hydroxide is KOH - also called lye.

potash is potassium carbonate is K2CO3.