Peppermint Essential Oil

A few weeks ago, I starting using Plant Therapy Peppermint essential oil.
I purchased a bottle of Peppermint (mentha arvensis) in December. First, I added a (one) drop to my hair cleaning solution and a couple drops to my conditioner solution.

Then I added some to coconut oil to create a salve. I melted the coconut oil by placing the little tin on my stove while cooking, so the heat would melt the oil. Then I stirred in about 5 drops of the peppermint oil. So far I have used it on my neck and in my hair (for fly away hair). That was because this is a scent I like and tolerate well.

That is as far as I have gotten with peppermint.
I also just received a bottle of Peppermint (mentha piperita). I am working on learning the differences. 
I have a thing about storage containers now. Well, honestly I have always liked containers. This tin actually came from an Advent calendar. I am not considering them food safe, but I think I will find many uses for them.

 Do you have any uses to share for peppermint oil? What about the differences between Peppermint (mentha arvensis) and Peppermint (mentha piperita)?