Zoning Code vs Building Code

Both Codes are mandated by City ordinance. The Revised Ordinances of Honolulu (ROH) has 41 Chapters. The Land Use Ordinance ("LUO") aka Zoning Requirements, generally address what a project looks and feels like. Whereas the Building Code is more concerned with life and safety issues.
Below are some of the more relevant ones to Real Estate and Construction.

• Chapter 16 Building Code (Article 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
• Chapter 17 Electrical Code
• Chapter 18 Fees and Permits for Building,Electrical, Plumbing and Sidewalk Codes
• Chapter 19 Plumbing Code
• Chapter 20 Fire Code of the City and County ofHonolulu
• Chapter 21 Land Use Ordinance, Exhibits and Article 10 (2.4 MB PDF) (Appendix A, B, C, D, E, F-Kakaako Special Design District, G, H, I; Index)
• Chapter 22 Subdivision of Land
• Chapter 23 Shoreline Setbacks
• Chapter 24 Development Plans (Ordinance provisions: Central Oahu; East Honolulu; Ewa; Ko'olau Loa; Ko'olaupoko; North Shore; Primary Urban Center; Northwestern Hawaiian Islands; Waianae) (Plan documents: Central Oahu; East Honolulu; Ewa; Ko'olau Loa; Ko'olaupoko; North Shore; Primary Urban Center; Waianae)
• Chapter 25 Special Management Area
• Chapter 27 Housing Code
• Chapter 32 Building Energy Conservation Code

According to the LUO, its Purpose and Intent is to:

"... regulate land use in a manner that will encourage orderly development in accordance with adopted land use policies, including the Oahu general plan and development plans, and to promote and protect the public health, safety and welfare by, more particularly:

(1)  Minimizing adverse effects resulting from the inappropriate location, use or design of sites and structures;

(2)  Conserving the city's natural, historic and scenic resources and encouraging design which enhances the physical form of the city; and

(3)  Assisting the public in identifying and understanding regulations affecting the development and use of land.

(b)  It is the intention of the council that the provisions of the LUO provide reasonable development and design standards for the location, height, bulk and size of structures, yard areas, off-street parking facilities, and open spaces, and the use of structures and land for agriculture, industry, business, residences or other purposes."

The LUO is also concerned with landscaping, min open space requirements, # and arrangement of parking stalls, residential/commercial density and use, and preserving certain features in a Special Design District. The LUO is what prevents your neighbor from opening an amusement park or night club next door to you.

On the other hand, the Bldg Code addresses "the design and installation of building systems through requirements emphasizing performance..." and fire-safety.

Both Zoning and Building Codes place restrictions on maximum heights, setbacks, floor area, but for different reasons. ie. The Zoning Code regulates floor area for aesthetic reasons, perhaps to limit neighborhood density, whereas the Building Code limits floor area to reduce the hazard in case of a fire. 

For example, a building made of concrete (w/ fire-sprinklers and multiple exits from each floor) would be allowed to be built taller, larger and closer to the property line, than a building made of wood. In case of fire, a concrete building stands a much greater chance of containing the blaze to a smaller area, thus allowing occupants to escape. Also, there is less chance of fire spreading throughout the concrete building or spreading to a neighboring lot.