The distinction between a container solution and mobile device management (MDM) is subtle but relevant. A container solution or container app is an app that employees can download independently onto their smartphone. The rules that apply within the container can, in turn, be defined centrally by the company. In this way, the user still has control over his or her private smartphone. However, the company can decide on the container environment and thus implement security settings at its discretion without interfering with the "private" area of the employees' smartphones. In addition, the apps and data are encrypted in the container, which in turn should have a strong authentication mechanism.
MDM is usually about controlling or managing the entire device, not just a specific area (as it is the case with a container). This is often used for business devices where private use is prohibited. When using private devices for professional purposes, however, it is recommended to use a container solution instead of a comprehensive MDM in order to i.e. protect the privacy of the employees.