Only Office 365 can upgrade to Office 2016 or Office 2019 or future Office version.
That meant Office 365 is the base version of Office 2016 or Office 2019 after your upgrade procedure finished.
In the market, the fastest way to have new feature for PC is Office 365. This is the only version will have future new feature
New Icon take time to come out from Microsoft. Some of the new icon is still testing, not yet come out for download.
Mobile or tablet version Office will be the first two complete have all new icons. PC take some more time for testing. I don't think anyone interest to have a lot of bug after install new icons. So When all new icons ready, You will get all download.