Each of the past few major upgrades to Odoo has brought with it new improvements to the reporting engine. Odoo 10 is no different, and many of the old reports are gone. However, Odoo still provides support for those older types of reports. In the previous screenshot, when you see a report type labelled RML or PDF (depreciated), that is a report that is still using the old reporting mechanism. You can still open up those older reports and make changes to them. However, most of the reports now use Odoo's new Odoo reporting framework, QWeb templates.