Windows 10: Win7 to Win10 upgrade vs fresh Win 10 install: is fresh truly better?

I recently did a Win 10 21H1 fresh install on a virgin M.2 NVMe drive and was surprised to discover a size of 28.6 GB (discounting the pagefile and hibernate files). This was considerably larger than expected based on research and my recollection of a Win 7 to Win 10 1909 upgrade. To check my aging memory I reformatted the drive and than did a Win 7 fresh install (using SIW2's 7updater found on Seven Forums) immediately followed by an in-place upgrade to Win 10 2004. [Note: I know it's not quite an apples-to-apples comparison but differences between 2004 and 21H1 could not account for the variances depicted below.] The fresh vs upgrade comparison is shown below (accomplished by mounting Macrium Reflect backup images). The windows.old folder is deleted, the pagefile.sys moved off of C:\ and hibernation disabled on the upgraded drive: Line items representing less than 1% each are not shown. As depicted the upgrade approach results an installed size over 30% smaller than a fresh install and the machine actually seems to boot faster (although that's subjective since I failed to actually run the reboot time test on the.fresh install before over-writing it). My interpretation of info gleaned here and elsewhere was that a fresh/clean install is presumed to be superior to an in-place upgrade due to elimination of old OS left-overs. Did I misinterpret the implied advocacy that a fresh install is preferable? Thanks in advance for your time and expertise.

:)

 

Fresh Install of Win 10 without Serial Key?

Looking to reformat a laptops HDD, and then reinstall Win 10 fresh. The problem is it came pre-installed with Win 8 and I did the free upgrade to Win 10. How exactly would I re-format the HDD, reinstall Win 10 and ensure it reactivates properly? I don't see a Win 8 serial key anywhere in the contents of the box.

 

Fresh Install of Win10 after Upgrade?

I've upgraded Win 7 Ultimate to Win 10 Pro. My system is running slow so I want to do a Fresh Install of Win 10. Question is How do I do it? How to create a Bootable usb of installed Win 10? and also I'm unable to see Product Key of my upgraded Windows?
Is there any Step by step guide to do that? Help me out!!!

 

Fresh Install of Win 10

I have a PC with Win 7 and I did an upgrade to Win 10 and it seemed to work fine except I wanted to do a fresh install and I did not see how to do a fresh install. So with this PC which now has Win 10 how can I do a fresh install?

Also, I have 2 other PCs (1 with Win 7 the other Win 8.1) how can I do a fresh install to start off with?

Thanks for your help.