What's the difference between and , and ?

Answer 1

and are both related to style, whereas and are semantic. In HTML 4, the first are classified as font style elements, and the latter as phrase elements.

As you indicated correctly, and are often considered similar, because browsers often render both in italics. But according to the specifications, indicates emphasis and indicates stronger emphasis, which is quite clear, but often misinterpreted. On the other hand, the distinction between when to use or is really a matter of style.