From Persil's website (bearing in mind that they sell the stuff...)

Bio? Non-Bio? What’s the Difference?

Whether you’re tossing up the difference between bio and non-bio laundry liquid or choosing between bio or non-bio capsules and washing powders, you need to first know what defines each of them.

What is biological detergent? Biological clothes detergent contains enzymes that help break down the fatty, greasy, and starchy compounds that are found in some of the most common clothing stains such as pasta sauces, bike oil, and hamburger grease. These enzymes work to lift the stains out of fabrics, making them excellent stain removers and a very welcome addition to laundry detergents, turning stain removal into a quick and easy task.
What is non-biological laundry detergent? Non-biological detergents do not contain these enzymes and can be kinder next to sensitive skin which makes them popular with families who have sensitive skin. Good non-bio detergents, like Persil, still contain powerful cleaning agents that will ensure your clothing comes out of the washing machine clean and fresh, you just might need to use a slightly higher temperature when washing with non-bio detergents – especially when tackling particularly tough stains.
As you can see, the main difference between bio and non-bio washing powders, liquids, and capsules is their use of enzymes.

What are the Advantages of Bio Detergent?

The advantages of bio detergents are undoubtedly their powerful stain removal. Biological clothes detergent contains enzymes that enzymes work to lift even the toughest the stains out of your clothes, like grass or chocolate ice cream. They remove stains first time, even in a quick wash at 30 degrees. This can help you to save time and energy but also helps to powerfully clean your clothes and bedding without turning the temperature high, which can damage more delicate fabrics.

If your kids are active (and messy), you can toss their soiled laundry into the machine with any Persil Bio detergent for a quick clean!

What are the Advantages of Non-Bio Detergent?

While the enzymes found in biological detergents are great at stain removal, they could cause mild reactions in those with very sensitive skin. If enzymes remain on clothing after a wash and rubs against the skin, some people may notice a mild reaction – however, this is rare.

The enzymes used in biological detergents are not used in soaps and body cleansers, etc., only in laundry detergents.

Note that Persil forget to mention that biological detergents are bad for septic tanks!