A terminal that deserves to be called smart is a graphics terminal which can rapidly display full-screen graphics just like a PC monitor. It will also have a mouse. It will often use a high-speed connection to the computer using twisted pair or coax cable. X-Window terminals are such devices. Winterm using WinFrame software from Citrix is one.
Hydra is also multiuser.
These are neither true computers nor terminals but are something in-between. They are full-graphics and connect to a server computer. They are different from terminals since the programs they run execute on their own CPU chips. Java code may be sent to them for execution. They should work on IP networks and might work under a server running Linux.