User variables are data points that users create and define for specific needs. They can represent a variety of information such as a URL, a name, a date, or any other specific data that the user wants to use regularly. These variables can be inserted into email templates or documents, and they will be auto-populated with the relevant data when used.

System variables are predefined data points set by the system. They represent common pieces of information that are frequently used, such as a prospect's name, a firm's name, or a link to a deck from a data room. These variables are automatically populated with the relevant data when used in emails or documents, streamlining the process of personalizing communications or documents.

To summarize, the main difference between user variables and system variables lies in their creation and purpose. User variables are created by users to meet specific needs and can be customized based on the information they want to use regularly. On the other hand, system variables are predefined by the system and represent common pieces of information that are frequently used across different users. While both types of variables are auto-populated with relevant data when used, user variables offer more flexibility as they can be tailored to individual user requirements.