I think this website is different from PDFtribute.net because it actually collects and stores the PDFs rather than just having links to the Twitter posts.
From the 'About' section of the website, you can see it uses PDFtribute.net to help scrape links.
We're working with the creator of edward.io to get some kind of integration between the two sites, and also working on a search/index/analysis tool for pdftribute.net
From the 'About' section of the website, you can see it uses PDFtribute.net to help scrape links.