The Connexium's web portal by 3CX is an online communication and collaboration platform that allows employees with extensions to manage their communication and collaboration needs from any web browser. It offers a range of features such as making and receiving calls, accessing voicemail, and sending and receiving text messages. Employees can also customize it and integrate it with other tools and systems such as customer relationship management (CRM) software.

On the other hand, the Connexium's desktop app by 3CX is a software application available for Windows and macOS that offers similar features to the 3CX web portal. It allows employees to make and receive calls, access voicemail, send and receive text messages, and customize their communication preferences from their desktop or laptop computer.

In short, the main difference between the 3CX web portal and the 3CX desktop app is that the web portal is accessible from a web browser, while the desktop app is installed as a standalone application on a computer.

Both tools offer similar functionality and features, but the web portal may be more convenient for employees who need to access their communication tools from multiple devices or locations, while the desktop app may be preferred by employees who prefer to have all their communication tools in a single, easy-to-use application.