Bonjour Anish (and Max) !

Max, I find it weird that you heard "Qu'est-ce" on its own, as it's very old-fashioned and antiquated...

The nuance is between "Qu'est-ce que + thing" vs "Qu'est-ce que c'est que + thing" to express "What is + thing":
"Qu'est-ce que la Tour Eiffel ?"
vs
"Qu'est-ce que *c'est que* la Tour Eiffel ?"

The first one is more formal as it's simply the inverted form (always considered more elegant), whereas the second one is more colloquial, and will be more used in everyday speech.
I would actually add that the most common way to ask this in colloquial speech would be a third option:
"C'est quoi, la Tour Eiffel ?"

I hope that's helpful!
À bientôt !

Bonjour Mary !

In the first case, you're asking confirmation that it is indeed the Eiffel Tower:

C'est bien la Tour Eiffel ?
or
C'est ça la Tour Eiffel ? (a bit more disdainful)

The second case is actually asking what the Eiffel Tower is:

Qu'est-ce que c'est, la Tour Eiffel ?
C'est quoi, la Tour Eiffel ?
...

Bonne journée !

Bonjour Anish ! It's not considered very elegant to use it in wirtten form: we'll prefer the "qu'est-ce que" option :) Bonne journée !