Testing some more. Let's see. Two spaces between sentences, same line.
New line (created by hitting the "return" key). One space between sentences on this line.
Again, with &br> tag to follow.
And again, same tag.
One more, with two line breaks.
OK, that's pretty clear. One line break, runs the paragraphs together. Two line breaks, leaves a blank line between paragraphs. A line break plus a &br> tag leaves two blank lines. (I'm not sure where the intentation came from.)
I have real work to do; this is cat-vacuuming, but maybe it's amusing if not helpful.