Do you mean Onedrive? It's not built-in but installed by default on Windows. It's still not as good as Dropbox. For example it only recently added differential syncing (for non-office files)[1] while Dropbox puts much more effort into syncing tech [2].
Most people probably won't notice the difference because the alternatives are good enough now. But if you have millions of files in deep folders, constant changes from multiple devices, or need instant syncing, then Dropbox is still worth the premium for the performance.
Most people probably won't notice the difference because the alternatives are good enough now. But if you have millions of files in deep folders, constant changes from multiple devices, or need instant syncing, then Dropbox is still worth the premium for the performance.
1. https://office365itpros.com/2020/04/28/onedrive-differential... 2. https://dropbox.tech/infrastructure/rewriting-the-heart-of-o...