Several roofers specialize in residential roofing service while others may specialize in commercial building roofing service. Many will specify in the commercial end of the business because they do not have to deal with individual home owners.
Also the jobs may be large. Another reason is that a lot of industrial or commercial roofing done is a form of laying down a sheeting product like corrugated metal or forty foot long sheets of flat metal shingles. Often the buildings can have a metal structure and they dont require special rafters or decking. This is not true of all commercial and industrial structures but of a lot of them.
A residential roofing service that specializes in roofing houses is usually who you would call to come and re-roof your home. You may also call on them to repair your homes roof should it be damaged or leaks. There are a lot of home roofing materials to choose from. If you have a residential roofing service can come and give you a quote they will suggest what roofing material you can use on your home. Generally most home owners might replace like with like materials. If you have asphalt shingles then you will replace the roof with asphalt shingles.
You may upgrade the shingles to a better quality or one with a longer warranty. Or you may are going to put on asphalt shingles that cost a bit more and perhaps look more like a shake roof. But generally you certainly will stay with the asphalt shingles.
One reason to stay with a like roof is that if you were going to switch to a concrete tile roof, your existing roof structure may not support the weight of these tiles. To get concrete tiles put on the roof you would have to have that roofing specialist build up the underlying composition so it can support that additional weight and this costs some money.
The same is true with other heavier roofing supplies, including some of the eco green roofs that are covered with living vegetation.
If your home already has a definite tile roof on it your then home has one of the longest roofing material warranties and it can previous fifty plus years or more. In this case, you may only require a residential roofing service if one of the concrete tiles breaks or is damaged by something, or a structure on the roof fails.