i installed E-OS on a drive with 128gb... and i want to leave this drive for the os only, and install apps(like steam-telegram etc) on the other drive 1 TB, i am coming from windows where as u know u can choose the directory for every app during the installation... but here u cant :( pls help me i dont want to go back to windows it sucks with ui... and i paid for eos cause i love it really
UNIX and Linux systems use a radically different way of making different volumes accesible. They typically have a unified filesystem hierarchy where different volumes are mounted in subdirectories under one common root folder ("/").
Traditionally Linux does not separate as much between the OS and third-party applications installed through the package manager. Instead the filesystem hierarchy arranges files and folders by their roles. For example, most applications will consist of one or more binaries plus data like images. They will also, most probably, make use of some libraries. On Windows, a program would be installed in one common location including all of that. However, on Linux the package manager will install the binary to /usr/bin, the libraries to /usr/lib, and data to /usr/share for example. This allows for better reuse of files, leading to a more efficient use of the space. Especially for libraries it also means better RAM utilization (because they need only be loaded once for multiple programs) and better security (because they get security and bug fixes once and are applied to all the programs that use them).
What many people do on (desktop) Linux instead is to separate between the OS (including all programs installed through the package manager) and user data. That means you would mount your 1 TB volume to /home. As for how to do that, there is some official Ubuntu documentation: https://help.ubuntu.com/community/Partitioning/Home/Moving
For typical installations 128 GB is way more than you will ever need for the OS including all programs. Normally, the big chunk of data is user data, like photos, movies, music, etc.