Your PC manufacturer may have customized the reset to restore all the pre-installed bloatware. Therefore, the fresh start bypasses bloatware and only reinstalls MS Store apps. By resetting your PC, you can perform a clean reinstallation and update of Windows while keeping your personal data and most of your Windows settings intact. In some cases, a clean installation can improve the device's performance, safety, browsing experience, and battery life.
The “Restart” option also allows you to reset your device if they have problems, but unlike the “Reset this PC” option. They will reinstall Windows 10 with the latest updates from Microsoft. Added in the Windows 10 creator's update, the Windows 10 Fresh Start tool replaced the system update. It is included as part of Windows Defender instead of the standard control panel.
Fresh Start allows you to perform a clean reinstallation and update of Windows, while retaining personal data and most of your Windows settings. It will remove most of the applications from your PC. The difference between Fresh Start and System Reset is that when you restart, Windows 10 is downloaded from Microsoft and is not extracted from the device's standard restore partitions. Generally, you'll want to use this option if you're setting up a new device and want to start from scratch without any third-party software or custom settings from the device manufacturer.
The “Reset this PC” option basically allows you to reset your device to its factory default settings, not to start from scratch. Generally, you'll want to use this option if you're setting up a new device and want to start from scratch.