In VPS hosting (virtual private server hosting), the customer has a partition on a larger computer with its own operating system. However, this is not the same as shared hosting.
In shared hosting, customers still have their own partition. However, it differs from VPS because it is the company that provides system administration. In VPS, the individual users are responsible for their own system administration. Having control over your own system administration has advantages. It is likely that you will be able to install whatever program you need for your website. There are usually, however, limitations placed by the hosting company to protect their servers.
In a VPS environment, individual partitions can be rebooted as needed. In shared hosting, the whole machine needs to be rebooted which caused downtime for all users on that server. Having control over your own administration has benefits here, as you will be able to plan your down time during non-peak hours. Also, with VPS, you don’t have to wait for patches and updates, but can install them as needed.