Selected answers from the Dumb SEO Questions Facebook & G+ community.
Benedito Rodrigues: maybe but https://www.searchenginejournal.com/google-treats.../254687/
Stockbridge Truslow: You`ve got to make sure you read the article in the above comment completely - because they are not "really" the same.
That said... with that many pages established, I`d imagine the hit (and recovery time) while Google regroups around the new location of the pages would be enough of a downside to outweigh any benefit from moving them (assuming that ranking is the primary reason for moving them). Plus, when in a subdomain or a subfolder - integrated navigation sort of balances it out. If they are not the same navigation and you move it from subdomain to subfolder - they are still likely to be treated very similarly to the current setup because they aren`t completely intertwined. If the navigation already matches, then they`re completely intertwines so a lot of the structural stuff is already accounted for.
Jayasanker Jayakrishnan: I second Stockbridge Truslow you can also consider adding a new resource section which is a sub directory.
Ryan Jones: No just changing it won’t help you. And there’s always a chance you mess up a redirect or 3 and it ends up hurting you.
All the correlation studies here are BS and don’t account for the differences in internal linking between sites that use the different methods.
Richard Hearne: If you`re starting out it *might* provide some benefit to use subdirectories over a subdomain. But moving 600K URLs (I`m thinking we`ve spoken before?) carries a lot of risk, while the potential reward is likely to be marginal at best.
Bigger question - how has your site got 600K URLs? Sounds like an automated generation process. Nothing wrong with that, just asking.
Mal Ö Tonge: 600k pages? I think you should be looking at other reasons why pages are not listing. Are they all unique? high quality better than anything already out there? 600k pages unless you have hundreds of writers and have been going for a few years or more I can not see how anyone can produce 600k words let alone pages unless scraping useless content from the web and spinning it. Remember quality over quantity is key! clicks no longer matter these days, if people like your site then Google will list your site, if users show Google negative signs about your site like leaving fast and returning to the search then Google will eventually drop you in the ranks.
No Matter the amount of adjusting to domains / subdomains / directories, that you do, Google will still see the content as the user sees it. The only thing you can do is to change content by optimizing with SEO starting with the pages most likely to rank. anything under 300 words I would merge together some how or just delete them completely and place 410. if it`s junk then put it in the bin! Simples!
Saurabh Rawat: Thanks everyone, your comments are very helpful for me. My all pages are auto generated. I have discussed with developer, a small code can redirect all my 600k pages without any risk. Small cost work for us. I have read many case studies on this, still it may help to improve minor ranking. So I am going to change url structure, subdomain to subfolder shifting with proper breadcrumbs. I know Google will take long time to change these all 600k pages which is fine, I don`t think it`s a problem. I will definitely share with you all my results and analysis.
Dan Thies: Saurabh Rawat you can not redirect without risk, period. It’s not going to improve ranking, and if you don’t handle the canonicalization before you redirect, it’s guaranteed to hurt.
Richard Hearne: The risk isn`t that you mess it up, although that`s also a risk. The risk is that Google will have no way to figure out what you`ve done and that it reduces your traffic.
Michael Martinez: There is no SEO benefit to moving content from a subdomain to a subdirectory. Everyone who has claimed such a benefit failed to mention they substantially changed the navigation structures on their sites, either removing "rel=`nofollow`" link attributes pointing to the subdomain or adding more links to the subfolder in the sitewide navigation.
If I change my 600k pages from sub-domain to sub-directory. Will it help me to improve ranking? 
