phd - What is the difference between a thesis and a dissertation?

I have seen some sites that distinguish a dissertation as what is written as the requirements of a doctoral degree.

Others that distinguish a thesis as a document written for the fulfillment of any degree (Bachelors, Masters or Doctoral) while a dissertation is a more general name for a document where someone is presenting findings.

I am curious if there is any more rigorous definition which distinguishes the two, but my more immediate question is this:

I am writing the document to fulfill a doctoral degree. Within the text of the document do I refer to it as a "Dissertation" or a "Thesis"?

For example: "A more thorough review of this analysis is presented in Chapter 5 of this ________."

Maybe the fact that the [thesis] is the tag used for all of these documents is an indication of the answer?

I've also seen this question on this site, but it doesn't seem to answer my question: What are the main differences between undergraduate, master's, and doctoral theses?