UEFI or Legacy?

So i went for a clean Windows 10 installation on my Aspire E13.
To boot from USB i had to switch from UEFI to Legacy, otherwise the USB drive would not be listed.

However. After the installation was finished my touchpad was not even recognized, i mean, i was not even listed in the device manager, so i read somewhere on the Acer forum that switching back to UEFI would solve this problem.
Well, i switched back to UEFI and now when the laptop start i recieve a message that says -No bootable device found!

Even if i try to use my bootable USB drive, the list is empty.
So i switched back to Legace again and guess what. Windows 10 starts like there was no problem.

So, what's the different between UEFI and Legacy? The bios tells me -Use UEFI on Win 8 and above to use all the benefits.
And why oh why can't i boot up from a existing and working Windows 10 drive using UEFI?

Depending how the Windows 10 install media is booted (UEFI or Legacy BIOS) Windows Setup creates either GPT or MBR partition style on the hard drive.

jebediah said:

To boot from USB i had to switch from UEFI to Legacy, otherwise the USB drive would not be listed.

First, check the file system of the USB flash drive.

The file system of the USB flash drive must be FAT32 if you want to install Windows 10 in UEFI mode.

USB Flash Drive - Create to Install Windows 10

Option One: Use Media Creation Tool to create Bootable Windows 10 USB for Legacy BIOS and UEFI
Option Two: Use "Rufus" to create Bootable Window 10 USB for Legacy BIOS and UEFI

@jebediah, what did you use to create the Windows 10 USB flash drive with? Most of the people I have asked who state they can't boot their computer in UEFI mode from a USB flash drive have responded that they made it with Rufus. In my opinion, Rufus has too many overly complicated settings that the user must set exactly correctly and in the correct order and it's too easy to mess it up, so I would not recommend anyone use it.

Create a Bootable USB Flash Drive

Make sure to read the important box at step 9 and use the FAT32 filesystem (which I recommend whether or not you are going to boot with UEFI):

9. To format the partition, type format fs=fat32 quick, and then click ENTER.

For step 12 you just mount the windows ISO file and copy all the files and folders from the mounted ISO file to the USB flash drive.

Thanks guys. I've always used Windows USB/DVD Download Tool and it has worked just fine for several years, even with other desktops with UEFI :/
However, i tried Rufus and it worked. The guide should be updated though since every time you choose the .iso file all the other setting get resetted :) Took me two tries before i noticed it.

Still there's something wrong with the touchpad that i have to solve.

jebediah said:

Took me two tries before i noticed it.

took me forever to figure it
and then i just noticed that after reading your reply lol
thanks man