What the fuck is the point of this thread?
Text-based? Do you even know what that means?
Obviously you must have mistaken PS:T and Fallout for a MUD or MUSH, or maybe even Zork.
Fucking idiot.
PS:T and Fallout are just as visual as they are textual, and what cannot be visualised completely is interpolated through text.
If you had ever played a MUD or MUSH you'd know the difference between text-based and visually based games, and how the fuck can core 'gameplay' even be text-based as opposed to visually based?
Gameplay revolves around mechanics themselves, and in many of the games you list, the functional aspects of gameplay are hidden, so that the player receives both visual and textual feedback.
When you hit an enemy in Torment, you get visual feedback, you land a blow and see a damage overhead to tell you how much HP damage you did- that does not make the gameplay textual, the text is there to give you feedback on a gameplay mechanic, that is, the calculation of your THAC0 against the opponent's AC and HP score, as well as a few other things (to simplify it slightly). When you kill the enemy, they fall to the floor dead. This is visual. Not fucking textual.
Textual gameplay involves the inputting of textual commands which function in a given context and give only textual feedback in a world fully simulated in text, so that the rooms you traverse, and any information you receive about them, your character, your opponents/allies are textual. This means you, using your imagination, to immerse yourself in the world.
And to answer the question, they function differently, you cannot even equate how one immerses you more than the other. If I read a fantasy novel and the author is of a high enough calibre to elicit suspension of disbelief and the creation of an imagined world in which you follow his narrative, then that is how the best textual game representation can and should also function. Visual media stimulate your brain differently.
As a footnote, I will also add that even textual games can be visual, given the development of ASCII. I used a piece of ASCII art as my character description (a drawing of a dwarf in full armour, with a battle axe)- ie: I offered other players a visual representation of my character which they would only be able to interact with in text.
Also, fuck you.
Edit1.: To even suggest that 'gameplay' can be visual or textual is fucking cretinous. Graphics and Text are not gameplay. Mechanics are gameplay. Graphics and text function as player feedback for implicitly or explicity present gameplay mechanics.
See PS:T example. Dialogue is a mechanic, the text of what you say in dialogue is feedback of how the mechanic works: ie, angry response, nice response, neutral response. If intimidation and persuasion are elements of the dialogue mechanic then these are represented textually (what the game shows your character saying), aurally (what the VO says) and visually, when the game shows your character collar grabbing an opponent. But none of these representations are fucking gameplay.