Because the word api Microsoft.Office.Interop.Word.dll does not count the same number of characters as the word

I use the word api Microsoft.Office.Interop.Word.dll and it does not tell me the same number of characters that the Microsoft Word tells me. Some of you may have an answer to this incognita that has been stuck in this for several weeks.

  Word.Application App = new Word.Application();
  Word.Document Doc = App.Documents.Open(ruta);   
  int totalP = Doc.Characters.Count;

I used the api and the count gave me 1 character however with the word it gave me 1674 characters with spaces (I want to clarify that my word file contains text boxes). Here is the file link