Regarding LT System

In what context and for what world market?

Usually when discussing SwitchGEAR here in North America, it is either fixed or draw-out. "Plug-in" would only relate to Panelboards and Load Centers, a step below Switchgear in the hierarchy of equipment.

Draw-out Switchgear means a very specific design criterea wherein the individual power breakers or switches are in completely isolated cubicles. When you want to work on a machine or system fed by a unit, you use a crank mechanism to "draw out" the cubicle away from the bus connection and lock it in that position. This is all done through the door so there is a limited exposure to arc flash.

Plug-in, as it would relate to a Panelboard, just means that the breaker or switch has a bus bar connection that does not require using bolts and washers to facilitate the connection. But you CANNOT disconnect a unit from the bus when it is live, you must kill power to the entire panelboard before making any changes. That's not to say it doesn't happen that way, but here in NA, that has become much more difficult now because of Arc Flash Prtection regulations.

If you are not referring to North America, I have no clue how these definitions might be different. Maybe you should have listed your location when you registered. But it's not too late!