https://www.zdnet.com/article/next-for-windows-10-what-to-expect-from-the-april-2019-update-aka-version-1903/?ftag=TREc64629f&bhid=20563615010054021886152894255900
 
Windows 10 version 1903, which was codenamed 19H1 in its Insider Preview testing phase, is the first update since Microsoft changed its support lifecycle late last year. The version 1903 update will have an 18-month support cycle for all editions, whereas the version 1909 release, due in October, will get a longer, 30-month support cycle for Enterprise and Education editions. (All Windows 10 Pro installations will be supported for 18 months, and Windows 10 Home has no ability to defer updates.)
 
In summary, version 1903 contains enough new stuff to earn its status as a major feature update. As always, you can manually update immediately, or you can wait till Microsoft releases the update to your PC, a process that might take a month or two. And, of course, you always have the option to watch and wait as Microsoft fixes the inevitable glitches and hiccups in those first few months.