A gaming computer, unlike a typical web browsing/word processing machine, will more often make use of a fast multicore processor, more ram, and will also include a dedicated graphics card.
Most desktops are capable of some basic workstation tasks. However, it would be best to have more robust hardware when using more intensive professional applications like Redshift.
As the name implies, a desktop system is a computer geared for usage at a desk space as they are stationary and user-focused for daily use.
While the use case can impact what makes a desktop suitable, generally speaking, a good desktop computer will have modern hardware focused on compatibility with the newest applications.