Windows 10 is very flexible and you can use any type of installation medium for installation but it is recommended to use USB Flash drive and external hard drive because now a days every computer doesn't posses CD Rom or SD card reader. Whereas, every computer has USB ports and USB flash drive and external hard drive can easily be connected to it.
its better
Explanation:
it just reccomends you instal an update to your windows to make it faster
USB Flash drive and External Hard drive
Explanation:
Windows 10 is very flexible and you can use any type of installation medium for installation but it is recommended to use USB Flash drive and external hard drive because now a days every computer doesn't posses CD Rom or SD card reader. Whereas, every computer has USB ports and USB flash drive and external hard drive can easily be connected to it.