Student or Learner
Are nachos and tortilla chips the same ?
Also, Can I say I want 1 nacho (= 1 chip)?
You could certainly ask for one chip, but I'm not sure why. You wouldn't ask for one nacho.
"Nachos" are a dish that includes tortilla chips, but they are not the same thing. In the most basic form, nachos are chips with a spicy cheese for dipping. Jalapeno peppers are sometimes an option. Alternatively the cheese is already poured over the chips.
From there, the dish becomes more elaborate, often called "nachos grande" or "nachos supreme" or something like that. Then the chips would be topped with cheese, jalapeno peppers, taco-flavored ground beef, sour cream, etc.
More elaborate nachos:
To make it more confusing, there are also pre-flavored tortilla chips in "nacho" flavor, which are coated with a powdered flavoring meant to simulate the flavors mentioned above (namely cheese and pepper). "Doritos" was the original brand name.
Nacho cheese-flavored chips: