A quick read of perlpodspec suggests to me that both versions are legal but are semantically different. The former is a list of named items equivalent to HTML <dt> tags where the term being defined includes the leading asterisk, whereas the latter is a bullet list of items equivalent to HTML <li> tags inside a <ul>. However, I'll be the first to admit to not being the best at reading formal specs so could be completely wrong on this.

That said, pod2html renders them identically (as <ul><li>...) so probably I am totally wrong in my reading of it. Either way it could be clearer and/or less ambiguous.