Answer(01):
technically, an HTML element is the collection of start tags, their attributes, an end tag, and everything in between. On the other hand, an HTML tag (either opening or closing) is used to mark the start or end of an element, as you can see in the above illustration
Answer(02):
h1, h2, , p, strong, link, style, script, header, footer, img, a, div, span, br, hr, b, i, u, sub, sup, del, mark, section, h3, h4, h5, h6,button. tablel, uol, li, nav, form, input, , tr, td, th, ul, br .......................Etc