Do you want the short answer? They basically mean nothing. You need to know your source and understand where the oils come from and how they are processed. There are only a few sources that we trust and only one source that we shop from on a regular basis.
The longer answer is that some of these words are trademarks and others, by definition, do not represent the standard that you would expect. For example, the words “Therapeutic Grade” and “Certified Pure Therapeutic Grade” are trademarks. They don’t actually mean anything. One of the large oil suppliers trademarked one term and the other added a few words and trademarked the other. There isn’t a certification process involved with one; it’s just a group of words that got stuck together and trademarked (look tor the trademark symbol behind it when you read those words). It’s not to say that the oils don’t have therapeutic properties. If they are 100% pure essential oils, they most certainly do have therapeutic properties, but these terms don’t actually tell us about the purity like we would expect. You need to know your source!
Then there’s the word pure as it relates to essential oils. It means that at least 5% of what’s in the bottle is pure essential oil. FIVE PERCENT!!! I would like to know that I’m getting more than 5% purity and, personally, I won’t settle for less than 100% pure. Words like natural and holistic also don’t abide by the standard that you would expect. You need to know your source!
Although all of these words might be used as you would expect them to be in some cases, there are times when they are definitely not. For example, it takes the petals from 60 roses to make 1 drop of Rose Essential Oil. I promise you that if you see a bottle of “Pure Rose Essential Oil” in the store for $5, that it is not 100% pure. I have also seen statistics about the amount of plants grown and the amount of essential oils produced and exported out of certain countries and it is appalling. Most of what is on the market is not the level that we want to be using on our bodies and in our diffusers. Knowing your source and how and where the oils are sourced is so important when using essential oils.