The common sauce used by the old school tavern places is usually a combination 50/50 of purée and pizza sauce. Traditional add in ingredients are : salt, sugar, black pepper, dried oregano, dried basil and most use a garlic powder.
Stanislaus is mostly the default mixing Full Red pizza sauce ( with or without basil) and Full Red tomato purée. In most cases water is added to get the right consistency, the sauces when used the next day get more water added due to the mixture becoming gelatinous due to heavy amounts of dried oregano and basil. The sweeter sauce is created by adding sugar and / or using Stanislaus Super Dolce instead of the Full Red pizza sauce. Super Dolce can be used alone as well and it’s quite sweet.
They pretty much taste the same and I put Palermo’s in the same category. I didn’t think it was exceptionally sweet but only been there once to try it out. I think it’s a classic mix of sauce, purée, water and the ingredients listed above, but I do not recall pepper.