Need Mobile SSH Termux Termius
Main purpose Dedicated SSH, SFTP, local tunnel and terminal client for Android. Android terminal emulator and Linux environment wit APT packages. Modern SSH client for Android, iOS, desktop and web-oriented team workflow.
Setup style Enter host or save server profile, then connect direct. Install packages like OpenSSH, set up shell tools, work from Linux-like command line. Create or sync host, key, snippet and vault through Termius app/account model.
Android terminal control Built-in extra key row, grid session, fullscreen pane, pinch zoom, text selection wit copy/share, Gboard suggestion, voice input and tmux-friendly scroll. Powerful terminal environment; behaviour depend on di tool and config wey you install. Mobile keyboard add-on, gesture, tab, autocomplete, snippet and polished terminal UX.
File transfer Built-in SFTP dual-pane transfer tied to di active SSH session. Use command-line tool like scp, sftp, rsync, or installed file utility. Built-in SFTP and host/key management.
Multi-session work Up to eight SSH session same time for Android grid. Use multiplexer like tmux inside Termux or remote shell. Tab and split-view workflow, depending on platform and plan.
Data model Local only saved server, credential, history, settings and log. Linux-like file system and package inside di Termux app environment. Encrypted vault for host, key, snippet, forwarding rule, known hosts and team sharing.
Best fit You want simple Android app to connect server, transfer file and keep session alive. You want full command-line environment for Android, and you comfortable to install and config package. You want cross-device sync, polished productivity, vault and collaboration.

Pick Mobile SSH when

You want direct SSH access from Android without setting up full Linux environment or cloud-synced account model. E good well well for saved server, SFTP, tmux session, and fast local tunnel workflow.

Pick Termux when

You need package management, shell, compiler, scripting, rsync, curl, Git, Python, Node.js or other Linux-style tool direct on di Android device.

Pick Termius when

You want commercial, cross-platform SSH workspace wit encrypted vault sync, team sharing, keychain management, snippet, and one consistent app on plenty device.

Sources: Termux describe imsef as Android terminal emulator and Linux environment wit APT packages and OpenSSH support for termux.dev. Termius describe SSH, SFTP, Mosh, Telnet, Serial, keyboard add-on, SFTP, encrypted vault and key management for im Android page and vault documentation.