Can using keywords AND tags on WP cause issues?

My site if self hosted but I use Wordpress software. I use 'All in One' SEO plugin and type my keywords in their, I notice I also have the option of adding tags. Are tags and keywords essentially the same thing? Wondering if I only want to use one or the other so as to avoid over optimizing or duplicate content issues?

Great question KingMonkey,

By and large, each site is different so there may not be a concrete answer. For wordpress however, tags are different from keywords in that they are there for users to more easily navigate your site and find content that is relevant to something else they were reading. Sort of like an internal keyword. I wouldn't worry about duplicate content and tags can help your readers discover more of your content.

This post talks more about the subject,

http://greekgeek.hubpages.com/hub/difference-between-keywords-and-tags

This one speaks directly to a Wordpress blog,

http://scottwyden.com/blog-post-tags-vs-keywords-and-tools-to-help/

Hope that answers your question,

Shawn