What is the difference between a variance and special permit?

A special permit is generally required when a proposed use, due to its size or external impacts, needs greater scrutiny by the Town and may require special conditions to mitigate its impact. The Board's shall not grant approval or special exceptions unless the applicant demonstrates that "no undue nuisance, hazard, or congestion will be created and that there will be no substantial harm to the established or future character of the neighborhood nor of the town". In making its special permit decision, the granting authority is limited to consideration of the criteria detailed in the ordinance. The Board may not refuse to issue a permit for reasons unrelated to the standards of the ordinance.

A variance is required if you want to change your property (dimensionally, not in use) in a way that is generally prohibited by the Zoning Ordinance and therefore requires an "exception". The applicant must show a hardship imposed by the ordinance which is caused by a unique condition of the lot or structure, and the hardship is owing to circumstances relating to the soil conditions, shape, or topography of the land or structure and especially affecting the land or structures, but not affecting generally the zoning district in which it is located – see Section 120-122. Relief may be granted without substantial detriment to the public good, and without nullifying or substantially derogating from the intent or purpose of such ordinance or bylaw. The criteria for a variance is very strict. Applicants may want to consider all other options before applying.