Reader Question: Difference between a moisturiser and a conditioner

A: Well you are right, there really isn't much of a difference as long as we are talking creamy conditioners (examples herbal essences hello hydration, aubrey organics honeysuckle rose etc)  and creamy leave ins (anything creamy looking e.g giovanni leave in, scurl, carefree curl, herbal essences leave in) . If the conditioner is not creamy then it is a whole different game because it could be protein or an oil mix or a silicone serum or just simply fragranced water (really!!).



The main difference between rinse outs and leave ins is



1. Rinse outs are usually made to deposit onto hair in order to temporarily repair and strenghthen it. The deposits also make the hair feel very soft.

2. Leave ins are designed to add a little temporary softness and make hair easier to manipulate but do not deposit much in order to avoid build up. 



I have made a little table listing the ingredients and their functions to explain in further detail

Ingredient and Function	Hair Conditioner (Creamy Rinse Out)	Moisturiser (Leave in Conditioner)
Water - Makes the product easy to spread. Will penetrate hair.	Usually around 80-90%	Usually around 80-90%
Fatty Alcohol such as cetyl alcohol, stearyl alcohol or cetostearyl alcohol - Main action in conditioner itself, stop the fat and oil from separating. Does add some softness to hair	Usually around 2-4%	Usually around 1-2%
Depositing surfactants such as behentrimonium chloride (advanced surfactant) or cetrimonium chloride.  Adsorb (not absorb) meaning stick onto hair creating a feeling of softness. Correct charge on hair due to shampoo use.	Usually around 2-4% (Usually deep treatments contain advanced surfactants)	Usually around 1-2% (Rarely if ever contain advanced surfactants)
Anti build up  surfactants such as stearamidopropyl dimethylamine - These tend not to adsorb onto hair and therefore less likely to build up. Good for slip	Usually around 2%	Not usually present
Repairing polymers such as silicone or polyquartenium (2-4%) - Adsorb onto hair, temporarily repair split ends. Excellent for slip.	Usually around 2-4%	Usually around 2%
Other oils (mineral oil and almond oil) - Add slip, help 'seal' in moisture	Usually less than 1% (not always present)	Usually around 2% (but can be much higher - 10%)
Preservatives, pH balancers and fillers (i.e the stuff you want to read - jojoba, aloe vera, herbal extracts)	Less than 1%	Less than 1%
Special Exemptions
**Humectants such as glycerin and aloe vera (many conditioners do not contain these in significant amounts but some do). Typically over 3% is necessary for a reasonable effect
**Hydrolysed protein or amino acids (such as glutamic acid) . Again, not all conditioners contain these, they are used to repair hair damage and can penetrate hair depending on size. Usually 1-2% in a rinse out conditioner and less than 1% in a leave in.

Sources
 

1.Book - Cosmetic and Toiletry Formulation

2.Book - Hair Care: Physiology to Formulation


3. Dow Corning Formulation