2BrightSparks is expert at the task of keeping a single data set stored in multiple locations matched up, a.k.a. in sync. The company's flagship sync utility for PCs is SyncBack. It's available in the $40 SyncBackSE 7 and the $55 SyncBackPro, which adds syncing with online storage repositories and other niceties to the mix.
Bland interface or no, SyncBack, whether -SE or -Pro, is as powerful and versatile a sync program as you'll run across. It performed flawlessly in every job I threw its way. A more modern appearance would attract more buyers, but handsome is as handsome does and by that criterion, SyncBack is a movie star.