Why is the word "manner" the right choice in sentence below? The same bird, when placed with a more dominant jay, acts in a very different {mode/manner}. Cambridge Dic. gives the definition of "mode' as "a way of operating, living, or behaving"; "manner - a way of operating, living, or behaving". I thought the difference is only in the register formal/not formal, but it seems there's something else? The sentence is from a mock test.