Rapid Wash vs. Perma Wash

Here is a question that means little in the end but I thought it would be interesting to find out. I have always used Heico Perma Wash but recently picked up Nacco's Rapid Wash. Being curious like I am I looked at the ingredients.

Perma Wash-Ammonium Sulfite, Sodium Sulfite
Rapid Wash-Sodium Sulfite, Sodium Sulfate

Does this difference in chemistry matter at all? Is there an advantage of one over the other in the end?

Curious to hear the opinions/facts on this.

Patrick

Cf. (there was a url link here which no longer exists)

And
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Thanks Michel. Je ne'en ai pas vu.

Tout le plaisir est pour moi. I'm not sure why recently I've been compelled to produce so much quoted information about HCA and washing, I think I should call Dr Freud...