The name roofing contractor came into effect as a verbal label that roofing company owners would use as a more elevated role other then the label "Roofer" It came into the industry around the late 80's, but is widely used today as an occupational label of a roofing companies main principal operator.
The difference is quite simple. A roofing contractor as stated to the left is a basic label role describing a roofing company owner. A CEO of a limited roofing company would use the name during consulting with high profile clients to regular clients of their own roofing business etc. Their field duties include, roofing contracts, the legalities of guarantees, and problem solving issues. They spend time with advertising consultants, and handle their companies roofers, managers, and equipment inventory of their operating company. They have experience with many types of manufactured products, and can run crews of roofers in various areas of the roofing industry.
Today they can even own or run multiple roofing companies that focus on different areas of the roofing industry. They work each and everyday in the roofing industry, even in the snow. After 20 years of service they can take a role of inspector or roofing consultant.
A "Roofer" is an installer of certain roofing materials. Some are experienced in working for many different roofing companies, but have limited experience with certain manufactured products. They can focus on mastering just one or two areas of the roofing industry, and can stay employed by a roofing company for part of the year by installing one or two specific roofing products. Roofers can also be labeled as "Applicators" when it comes to certain roofing manufactures. They don't normally deal with consumer related matters, and their personal liabilities are very limited to the home-owner of the property they are working for on behalf of the roofing company.
They can however become a certified installer of a product if they take a manufactures written exam. If they pass the test, they can be issued a laminated card showing credentials as-well as the manufactured product name, and line.