UBI minimal is smaller than the UBI ones and as the name says has the minimal as possible. So, because of this, they are better to be used in containers.
The difference between them is that the minimal will not have some commands as “yum” to install the application requirements for example.
How to use UBI minimal to run applications in a container since it does not allow to install its requirements?
The best approach would be adopted multi-stage docker builds where the no minimal images may be used to do the builds, install all requirements and etc… them just what is required in order to run the application can be copied to the minimal image which will be used by it. See here an example.
NOTE: If you are asking what exactly is UBI then I’d like to suggest you check the blog post Introducing Red Hat Universal Base Images