How can I boot from Mac OS to windows with out restarting computer

[Smith07]

How do I switched from Sierra to windows 10 with out restarting computer.
When I boot to Mac OS I can see Window hard drive, when I boot to window I don't see Mac OS hard drive.

 

[bmoag]

This is elementary stuff:
A computer will only run one OS at a time.
There is at least one huge desktop case that can house two separate motherboards if you want to run two OSes at the same time and switch between.
Also KVM switches for two separate machines to use the same monitor/mouse/keyboard.
If you want to write to Windows NTFS files from within OSX the easiest way is to buy a program that does that, e.g Paragon (I use it) for NTFS--OSX can read but not write to NTFS formatted drives. Similarly if you want to access OSX journalled drives from within Windows . . .
If you want to run Windows programs, not games, from within OSX emulators sort of work, like, ugh, Parallels--that requires a complete install of the Windows OS into the virtual machine. The use of Parallels will burn into most people's minds the meaning of the word "kludge" and gift the experience of low level ransomware from the vendor (when you upgrade to the latest and greatest OSX you have to pay for the corresponding Parallels upgrade that doesn't work any better than ones you already paid for).

 

[Smith07]

I just want to switch between system, so I don't have to reboot and choose different systems in clover bootloader.
I don't want to operate 2 operating system in same time.

 

[cmn699]

I just want to switch between system, so I don't have to reboot and choose different systems in clover bootloader.
I don't want to operate 2 operating system in same time.

Like bmoag said , "Parallel" may the one closest to what you may want. It will run "Windows Applications" in Mac like "Wine" in "Linux" . But if you have two OSes on separate disks, you cannot 'switch' between the two system disks using Parallel or any currently available software.If you want to access (read and Write) files from the other System with a different filesystem, you will need NTFS driver in your Mac and HFS+ driver in Windows . bmoag has already given you the best software currently available for that: Paragon NTFS for MacOS X and Paragon HFS+ for Windows. They are not freeware!

 

[JCMunsonII]

But if you have two OSes on separate disks, you cannot 'switch' between the two system disks using Parallel or any currently available software.If you want to access (read and Write) files from the other System with a different filesystem, you will need NTFS driver in your Mac and HFS+ driver in Windows .

This may be an English language issue, however, that is not technically correct.

I use Parallels and run Windows 10 in a VM just fine with it. I don't find it any more "ransomware" than many other pieces of software around these days.

Regardless of that opinion, you CAN switch between two OS's on separate disks - IF you are running something like Parallels to operate the VM. That VM can easily be stored on a separate disk (which is how I have mine configured).

What you absolutely can't do is boot into macOS, then also boot into Windows outside of macOS. You MUST use some sort of VM manager to use both OS's at the same time.

Parallels ALSO contains tools to allow you read/write to Windows-formatted drives/partitions - especially when both are active.

So, in short, you can dual-boot (meaning have both OS's installed on your on physical hardware, but only using one-at-a-time), OR, you can run a VM wherein lies an instance of Windows (assuming Mac is your priority).