This came about because of some other threads.
Was looking at two recent 4.5 installs I did and guess what I did One in Legacy and the other EFI
So thought I would post for info purposes maybe it will help out.
If you use this command on installed systems will tell you what your system is using.
-d /sys/firmware/efi ] && echo "Installed in UEFI mode" || echo "Installed in Legacy mode
This is a Partion Setup legacy (Win10 overwrite)
This is a Partion setup EFI (New SSD never installed on)
You can tell the difference between them mostly the boot Partitions (Size In blue)
Single Os install whole disk
Hope this is of Use.