Difference of On Deck and Continue Watching

I would like to know what is the difference between Coninue watching and On Deck. At latest version of Web Player and Apple Tv app on my Home screen I get the last three movies I stoped on Continue Watching and some series episodes on On Deck. I don’t get it. What is the point? I have about 20 movies and several series episodes that are half watched but I can see them only under their categorie. Is it possible to have all my half watched movies-series under Continue watching and not only the last three? I’ts very confusing for members of my family to search every time the categories for their half watched media.
And how On Deck is working?

Thanks