Pavement breakers and jackhammers are the same kind of tool.
They are useful construction tools that are designed for specific jobs.
Figuring out which tool to use can be tricky. You need to think about the area that you will be using the tool in, and how ‘serious’ a job it is.
In most cases, pavement breakers and jackhammers are categorized by weight class. For example, an 80-90 lb pavement breaker would be used on streets, highways, commercial building foundations and other areas where it is difficult to get large construction equipment set up. They can break concrete or rock in excess of six inches thick.
Meanwhile, 60-80 lb pavement breakers are used for residential driveways and streets, and can be used on highways, but only in areas where the concrete does not exceed six inches in thickness.
There are 35-40 lb pavement breakers, and these are used for small jobs such as removing squares of paving stones, and other smaller similar jobs. These are useful for DIY enthusiasts who might want to repave their driveway, but they are not going to be of much value as a main jackhammer for a large construction project.
There are both pneumatic and electro-mechanical versions available. It is not uncommon for smaller pavement breakers to be powered by electric motors or even by compressed air, but the larger ones will usually be powered by hydraulics.
They work using an up and down motion. The internal hammer in the jackhammer will strike a bit to force it down, then be pulled back up to return the hammer to its original position. This process is carried out with a lot of force, and very quickly, to produce the striking motion that will break up the pavement or the concrete.
Hydraulic jackhammers require careful maintenance, but are the most powerful.