Government coding schemes were developed for purposes of tracking industry productivity, employment, growth, etc.
Business and trade publications, as well as trade associations, compile all manner of company rankings.
To find rankings, go to Business Insights: Essentials and go to Advanced Search to search by company name or a 5-digit NAICS code. Use the Content Type drop down under Select Limiters to find Rankings or Market Share data for major competitors in an industry.
Comparables within broad industry sectors are used by equity analysts for purposes of comparing public companies' performance.
To find industry reports by brokerages/equity analysts, go to Investext on the Mergent Online platform.