The Considerations section states that "The main difference is that the dmd's back end is not FOSS (licensed from Symantec), while the others compilers are completely FOSS."

However, compiling the source on this page using dmd is quicker and the results in a far smaller executable:

diederick@bob:~/projecten/d/ $ time dmd hello.d 

real 0m0.439s
user 0m0.380s
sys 0m0.053s
diederick@bob:~/projecten/d/ $ time gdc hello.d 

real 0m1.015s
user 0m0.920s
sys 0m0.090s
diederick@bob:~/projecten/d/ $ ls -lh
totaal 3,6M
-rwxr-xr-x 1 diederick users 2,8M 9 jul 12:53 a.out
-rwxr-xr-x 1 diederick users 642K 9 jul 12:52 hello
-rw-r--r-- 1 diederick users 99 9 jul 12:18 hello.d
-rw-r--r-- 1 diederick users 121K 9 jul 12:52 hello.o

Some might consider this the "main difference".

—This unsigned comment is by Diederick76 (talk) 10:56, 9 July 2014‎ (UTC). Please sign your posts with ~~~~!