I am wondering which site architecture I should use for blog. blog.site.com? or site.com/blog to get a better ranking Is there any difference at all? ------------------------------------------ also 1 more question is there a difference for SEO - site.com/keyword/ site.com/keyword.html
that really depends whether you are wanting to seperate the blog from the site or want to make it a part of your site. if you want the blog to be a part of your site as an addition, then site.com/blog would be better
It would be good if you create it as site.com/blog this drives more traffic by serach enigines. And second question answer no not more differences.
If you use site.blog.com then the subdomain (site) will class these pages as a whole different website! So: site.blog.com would be classed as a different website than site.com which is very bad for SEO site.com/page.html is the best way to go and don't use separate folders for each page as you'll have issues editing your site in the future and problems referencing images and other pages