i'm a little new to this topic, i've always used to work with responsive design to do this but for a new situation i have to change the content that will load on Mobile Devices than regular PCs, My Control Panel is Direct Admin on Windows server, what i should i do?
check out this answer on how to redirect mobile users to a different site - Redirect mobile devices to alternate version of my site
In addition to this I'll also chime in with the fact that people will browser most sites on both the mobile and the desktop, starting the journey on one and finishing it on another. They might also find something useful on one which they share online, only for another device type to be used when trying to read the content.
These are all reasons why we argue for content parity.... the same content for every instance. I'm sure your client believes they have a good reason for this, but I would encourage them to re-evaluate the decision before starting this process.