In the market, we have three common types of air compressors, which are for the garage or house; on a construction or job site like in a industrial or mechanical shop. The type & size is normally based on the place you use the air compressors.
For the garage or house, a small inflator or a portable air compressor will be good enough for you. Well, a small & simple inflator is used to inflate things like toys, sporting goods such as basket ball. However, one of the disadvantages of inflators is the slow speed. If you are looking for faster inflation in running a small air tools, such as air brushes or nailers, a portable one is more suitable and save time.
For other job site or construction, you may need a bigger air compressor to power multiple spray guns, nailers, sanders or other tools. We would recommend you to get a compressor that has a higher CFPM (cubic feet per minute) of airflow than the tools you plan to use. For example, a spray gun may need 4 CFPM of airflow to work properly, so the air compressor you are buying must be able to produce more than this much air in a shorter time. For high usage on a lot of job sites, you may also consider to get a contractor grade & truck mounted so air power is always available for your needs.
For shop, stationary or industrial setting, we may recommend you to get a bigger capacity air compressor. There are many types of industrial compressors in market including single stage, multi-stage, twin stack, wheelbarrow, pancake, rotary screw etc. Normally this huge size is centrally located so that it can work with many air tools and wide ranges of machineries.