Even though my dictionary regards them both as a shampoo, I wonder if 洗发剂 is more a conditioner for the hair and 洗发水 more a regular watery shampoo?
Is there a difference? Thank you.
I have some more:
They all mean shampoo. If there is any difference, that might be frequency or regional preferences. The last one is a loanword (香波)
Yes. They are the same. They are both for shampoo.
Conditioner is 护发素。 Conditioner is not intended for cleaning hair so it is not related to 洗 or any character with a similar meaning.
PS, If you want, you can even create your own word for shampoo as long as it makes some sense.
For example, you can say 洁发剂, which you can't find in any formal dictionary. But most people will still be able to get your meaning. It sounds a bit strange and likely makes people think you want some special kind of shampoo though.
Just to add to Drunken Master's impressive list, mdbg also has 润肤乳 as body shampoo and 洗发粉 as shampoo powder. I've never seen shampoo powder!
Conditioner they have as 'protect hair milk 护发乳‘， among others.
Don't bother memorizing their differences, I usually just regard them as one thing. However, the last character actual indicates its texture--pure liquid, sticky, extraction etc.
I think "剂" makes Chinese feel more about chemistry while "x水" is more oral in daily life with any form of liquid.