I know that the difference between the two used to be that Google basically rewarded those that used Wordpress Blogging, but really it isn't about either one.
As far as I understand it, it is about SEO, Content, Linking within the site, and linking to other sites, and compliance with W3C rules and speed of loading the pages, among other things that really have nothing to do with HTML or Wordpress as the platform.
WP is easier to use, but for the average html user, HTML is actually not that hard once the site structure is developed. The rest is just adding pages, just like wordpress. I think the main difference as far as ease of use is that WP is more out of the box and easily added upon, where HTML needs to be designed, and then added onto (as far as plugins) manually.