The first option allows you to select for yourself exactly what drives and partitions you want to include in the backup image. The second options tells Reflect to select for you and to include in the backup image only
those partitions that are required to boot the Windows operating system normally and nothing else
. Your own drive/partition selections (if any) have no effect on that second option.
In your case, the second option would include everything because both of the partitions on your single drive are required to boot the operating system itself. In other cases, the second option would exclude
from the backup image any partitions such as might be created on the same physical drive for some installed applications, for user data (docs, images, music, etc.), or for booting to the Windows repair and recovery (WinRE) environment. It would also exclude any additional physical drives and all of their partitions, of course.
Regards, Richard V. ("Arvy")