Does Thriller really mean Horror?

When we use the term Thriller, does that really mean it is a horror book?

The dictionary describes horror as :
HORROR. 1 a : painful and intense fear, dread, or dismay

Thriller is described  as:
Thriller is a genre of literature, film, and television programming that uses suspense, tension, and excitement as its main elements. Thrillers heavily stimulate the viewer's moods, giving them a high level of anticipation, ultra-heightened expectation, uncertainty, surprise, anxiety and terror.

 Fear versus Terror; what is the difference?
The key in my mind,as the Author, is in the details, In a Thriller, the police officer finds a murdered body; in a Horror book the murder is described in detail. Same thing has happened but one is intent on plot development, whereas the other is intent on making you squirm with horrid details that upset you to the point your mind is traumatized.

Horrible things are reported on the news every morning but we don't consider the news story a horror story. The fact that there are horrible people doing horrible things is a fact of life. But if I am intent on describing those horrible things, I am crossing over from suspense to gruesome.

As a Thriller, I promise to not cross over that line. I  may create dread, anxiety and fear as you follow the main character through the plot line, but I'll never make you feel you are reading a horror book or plot line.

Horror films and books have to use gruesome details simply because they do not have the ability to intrigue through character development, to the point you really do care about the person, who's life you've entered into through the pages (or screens in this age) of that novel.

My favorite feedback that I get on my books is, "I couldn't put the book down, had to read it to the end and was up all night." That is when I have done my job as a Thriller author.