Why is odt word count less than text?

[joe at actionline.com]

Why is it that when I import a text file into libre office and then
export the same text as an .odt document, the resulting document has a
smaller word count and smaller character count than the original text
file has?

Then if I save the same .odt document as a .txt file, the resulting .txt
file is bigger than the .odt file (actually almost the same size as the
original text file).