The format of a first$-$level heading is different from a second$-$level heading in which significant way? Every letter in a first$-$level heading is capitalized, and it appears at the top of a page. A second$-$level heading is left justified, but a first$-$level is centered on the page A second$-$level heading uses no capital letters. A first$-$level heading cannot appear at the top of a page. A second$-$level heading is twice as important as a first$-$level heading.