That's an excellent question. Let's first look at the descriptions of each condition.

From the CCHS Family Network website: http://www.cchsnetwork.org/

CCHS, or Congenital Central Hypoventilation Syndrome, is a disorder of the central nervous system where, most dramatically, the automatic control of breathing is absent or impaired. A CCHS child’s respiratory response to low blood oxygen saturation (hypoxia) or to CO2 retention (hypercapnia) is typically sluggish during awake hours and absent, to varying
degrees, during sleep, serious illness, and/or stress.

"...Studies suggest that between 10 and 17% of CCHS children require 24-hour ventilatory support.

"...A study of 196 CCHS patients suggested that seizures (42%), recurrent pneumonia (41%), developmental delays (45%), learning disabilities (30%), fainting episodes (25%) and irregularities of body temperature control (43%) occur in significant numbers of CCHS patients, along with other medical issues."

According to this journal article (http://linkinghub.elsevier.com/retrieve/pii/S0929664609602187):

Congenital central hypoventilation syndrome (CCHS) is a rare disease that is characterized by failure in the autonomic control of breathing. Recent reports have identified mutation of the paired mesoderm homeobox protein 2b (PHOX2B) gene as playing a major role in CCHS. Increasing polyalanine repeat number is associated with a more severe clinical phenotype.

As for Infant Sleep Apnea, the following is excerpted from this Stanford University webpage: http://www.stanford.edu/~dement/infantapnea.html

...characterized by central apneas or obstructive apneas that occur while asleep. An apnea is the stoppage of airflow at the nostrils and mouth lasting at least 10 seconds. A central apnea is when respiratory efforts stop for more than 10 seconds (20 seconds in infancy). An obstructive apnea is when the upper airway is blocked.

The diagnosis of 'Apnea of Infancy' is reserved for infants who are older than 37 weeks (approximately 9 months) at the onset of the apnea and for whom no specific cause of apparent life-threatening event (ALTE) or apnea can be identified.

'Apnea of Prematurity' is restricted to apnea in infants younger than 37 weeks (approximately 9 months) and not due to an explainable cause except respiratory immaturity.

What are the symptoms?

Observed cessation of breathing during sleep that may include:
-Color change (Infant is pale or bluish)
-Tone change - limpness
-noisy breathing during sleep

WHAT IS THE BOTTOM LINE? I'm not a medical expert -- maybe one will weigh in -- but it appears that CCHS is a more severe and rare condition, with a high rate of comorbidities.

As for sleep apnea, it's said to have many different causes, depending on which expert you talk with. Some cases are caused by obstructions (excess or slack throat tissue, particularly in obese patients or those who consume alcohol). But some are related to the neurotransmitter dopamine and its role in regulating the respiratory system.

In my experience (years of talking with people who have both ADHD and sleep apnea), many sleep experts are more prone to focusing on "obstructive" causes and don't always understand the role of dopamine. Because dopamine is the key neurotransmitter involved with ADHD, it's doubly important that people who have both conditions consult a specialist who understands the connection.

A quick Google search for "CCHS + dopamine" results in book citations, the links for which are too long to include here. In other words, it might not be out of the question that dopamine is related to CCHS, too.