An HOA, or Homeowners Association, is accountable for enforcing the deed restrictions and overall neighborhood conditions and regulations. A monthly, quarterly or yearly HOA fee, per homeowner, is used to enforce architectural review guidelines, and can be used for specific committees or social clubs (i.e. gardening, happy hour, yoga, etc.) within the neighborhood and is paid separately from your mortgage or property taxes.
The CDD is a government entity whose purposes is to finance, build, operate and maintain community-wide infrastructure elements, improvements and services for the benefit of the residents. CDD fees are included in the annual property tax bill as part of the non-ad valorem assessments.