Are "essential oils" the same as "fragrance oils"?
Also, I've been looking into natural cleaning products and in my notes I have written "castile soap (cornstarch)." Can someone help me figure out what I meant? Those aren't the same thing, are they? Or could I substitute one for the other?
Thank you.

Essential oils vs. fragrance oils

Castile soap and corn starch are not the same thing, but are both used as natural ingredient cleaners. Was there something you wanted to clean that involved both of them?

The only thing I might be able to add here is that somewhere I heard the cornstarch is use as a fine abrasive and used for cleaning something.

That with the soap may be good for cleaning something. May be oily skin. Castile soap has a high ph and not recomended for use on hair as it will dry it out.

Thanks for straightening me out. I have no idea what I meant about castile soap and cornstarch. Oh well. Where would I find castile soap, though?
Of course essential oils and fragrance oils are different. Why would anything be simple???

Thanks for the info, both of you.

Dr.Bronner's is an excellent castile soap, available in both a liquid and bar form and in several fragrances (Uhm, lemme think- lavender,peppermint, almond oil, unscented and there's one more that I can't remember) The product line is available in many grocery stores and nearly ALL health food stores in the personal care aisles.

I have seen a different brand of castile in the laundry aisles at the supermarket, but I can't recall the brand, just that it's in a very old fashioned looking wrapper- white with (I think) red printing.

Thanks for the info. I will check outthe grocery this week. As many times as I go there, I never know where to look for half the things -and forget about asking one of the employees for something slightly abnormal. They look at me funny when I ask for stir fry sauce.

Some essential oils are fragrance oils. That means that the volatile component has a molecule that will cause a reaction in a receptor molecule in the nose.

"Essential" just means that the oil is an essence of some cruder oil or product that has been extracted by steaming the crude source and collecting the essence by cooling - like distilling. But not all fragrance oils are essential oils. Some are cold pressed to extrude the oils. Here is a site that gives good details, and also shows how toxicity is measured on the LD scale.
Chemistry point of view.
For example, if a set of lab rats is fed a substance, and 50% of the rats die , that substance's toxicity (LD50) is rated based on the quantity fed to the rats. E.g. the LD50 for spearmint oil is about 1.6g/kg.

This toxicity scale is used to decide which oils are probably suitable for use on humans either ingested or applied to the skin.

(P.s. That's why I don't use cosmetics that are tested on animals. It isn't worth it to smell pretty.)