This has been especially true in the last 5 years. Generally when you purchase a Mac computer, you should buy the best that you can afford at that time. High Sierra, macOS 10.13, which will arrive in Autumn 2017, will bring even more speed boosts for Fusion Drive.
Fusion Drive handles all this in the background, automatically.
You will see much shorter startup times for your Mac, and as the operating system learns how you work, you will also see applications launch faster. The Fusion Drive is able to automatically move commonly used files to the faster Flash storage, for almost immediate access, while less commonly used files move to the hard disk. Your Mac will see the Fusion Drive as a single volume, but it’s actually consists of a conventional hard drive and super fast Flash storage. Fusion Drive is a new type of storage for some models of MacBook and iMac computers, that has the performance of Flash storage, but with the capacity offered by a hard drive.
