It's still confusing, but this at least helps/tries to clarify.

TTY is right there in the name, but this article makes no attempt to clarify what exactly the relationship between a pseudoterminal and a TTY. I feel like a whole paragraph about the relation to TTY would be warranted, including a link to TTY article, of course, which does link [back] to and explain some of the relation to pseudoterminal:

In many computing contexts, "TTY" has become the name for any text terminal, such as an external console device, a user dialing into the system on a modem on a serial port device, a printing or graphical computer terminal on a computer's serial port or the RS-232 port on a USB-to-RS-232 converter attached to a computer's USB port, or even a terminal emulator application in the window system using a pseudoterminal device.