From NAICS to NIC: How National Industry Codes Diverge

From NAICS to NIC: How National Industry Codes Diverge

TL;DR: Five major economies, five industry classification systems, same economic activities - but different structures, different granularity, different philosophical choices. This post shows where they align, where they diverge, and why that matters for cross-border data.

The five systems

graph TD
  ISIC2["ISIC Rev 4\n766 codes\n(UN global reference)"]
  NAICS2["NAICS 2022\n2,125 codes"] -.->|influenced by| ISIC2
  NACE2["NACE Rev 2\n996 codes"] -.->|1:1 at 4-digit| ISIC2
  NIC2["NIC 2008\n2,070 codes"] -.->|adapted from| ISIC2
  ANZSIC2["ANZSIC 2006\n825 codes"] -.->|adapted from| ISIC2

All five share the same conceptual DNA - influenced by ISIC. But each was adapted to reflect the economic structure of its region.

Where they agree

At the broadest level, all five recognize the same major sectors:

Where they diverge

Granularity

graph LR
  subgraph NAICS_AIR["NAICS (granular)"]
    N1["481111\nScheduled Passenger Air"]
    N2["481211\nNonscheduled Charter Air"]
  end
  subgraph ISIC_AIR["ISIC (broad)"]
    I1["5110\nPassenger air transport"]
  end
  N1 -->|many:1| I1
  N2 -->|many:1| I1

Translating from NAICS to ISIC is inherently lossy - multiple NAICS codes collapse into one ISIC code. Going the other direction, one ISIC code expands into multiple NAICS codes, and you cannot determine which one without additional context.

Structural differences

The technology problem

graph TB
  subgraph NAICS_TECH["NAICS"]
    NT["5415\nComputer Systems Design\n(catch-all)"]
  end
  subgraph ISIC_TECH["ISIC"]
    IT1["6201\nComputer programming"]
    IT2["6202\nComputer consultancy"]
  end
  NT -.->|partial| IT1
  NT -.->|partial| IT2

All five systems struggle with technology. Software development, cloud services, AI, and digital platforms are classified differently because these industries did not exist when most frameworks were designed.

This is one reason WorldOfTaxonomy includes 400+ domain-specific taxonomy systems - they fill the gaps where the major systems lack granularity.

The crosswalk challenge

A simple code-to-code lookup is not enough. You need to know:

Practical implications

Exploring the differences

# Compare NAICS and ISIC at root level
curl "https://wot.aixcelerator.ai/api/v1/compare?a=naics_2022&b=isic_rev4"

# Find NAICS codes with no ISIC equivalent
curl "https://wot.aixcelerator.ai/api/v1/diff?a=naics_2022&b=isic_rev4"

Or use the crosswalk explorer visualization to see the connection density between any two systems in the graph.