Truckmount carpet cleaning is more powerful than portable carpet cleaning. The reason truckmounts are more powerful is because they get their power from an engine, whereas portables use electrical sockets in your home.
Water pressure is the next difference between portable and a Truckmount carpet cleaning. In order for your carpets to be cleaned effectively the cleaning solution must be rinsed out completely. If it is not, then the remaining solution will collect soil, causing your carpet to get dirty faster. A portable is usually capable of 125-150 PSI. A carpet should be rinsed at 300-400 PSI, which a Truckmount is more than capable of achieving; it can go as high as 3000 PSI. The higher PSI helps to agitate the fibers, spots, and oils and soil to better remove them all.
Vacuum power is the next difference between the two machines. Truckmount carpet cleaners have much more power than portable machines. Even though truckmount carpet cleaners have higher water pressure, the vacuum is powerful enough to have most carpets completely dry in 4-6 hours or less. Portables Do Not have this capability. Most portables require overnight to be the recommended dry time.