Do you mean Haidong Gumdo or Kumdo?
The characters for both Gumdo and Kumdo are the same. It is the same difference between Celtic with a hard 'C' which is pronounced Keltik or 'Celtic' with a soft 'C', which is pronounced 'Seltik.' Both mean the same thing and are spelled the same, but in most parts of the US, unless you're speaking with an historian, most will associate the hard C pronunciation with Celts of the British Isles and the soft C with the Boston basketball team.
If you mean Kumdo, as in Korean Kendo, I can answer for you: yes, in Kumdo, we spar. Sparring is performed in hogu with a juk-to and conforms to the FIK kendo rules.
The top of the head, the wrists, the middle of the torso, and the throat are all valid targets. If the juk-to is held in joong-dan postition (middle guard with the point level with the opponent's throat), then only the right wrist is a valid target. In sang dan (high guard), both wrists are valid. The mok, or throat, is only valid with a thrusting attack. Strikes are performed with a stomping strike and in a walking stance with both feet pointed forward.
Now, if you're talking about haidong (or haedong) gumdo, last I heard, they do not spar. Haidong Gumdo is a lot more like kenjutsu in that it focuses on how a warrior would have fought on the battlefield rather than having focus on the fencing aspect. To my knowledge, the techniques are Korean techniques using the Korean daedo, which is similar to the Katana, so HDGD is not Korean kenjutsu (to my knowledge). BUT, there was talk of introducing hogu for Haidong Gumdo by one of the HDGD federations.
Ninjamom is a senior HDGD practitioner and is the best source on this board that I know of on the subject, so I hope that she'll chime in and clarify.
If you are talking about another 'gumdo', I have no clue. Given that 'gumdo' literally means 'sword way', any Korean sword art can by called gumdo.
I hope that helps.