Delve is the mega-search option for Office 365. In the past, Delve has been handicapped because of poor user tagging of documents. Apply some Office Graph intelligence, and now Delve gets better results. Magic!
Microsoft has long used OWA as the test-bed client for new features. After all, it’s easy to update a web client. Now they’ve added the ability to integrate content stored in Office 365 Groups in OWA searches. It’s a nice feature, as is the message digest for Office 365 updates that you can have sent to your mailbox.