Please don't read the rest of this post if you find cold details offensive.
I did a great deal of research at the time and later something bigger.
I lost a friend in the towers, and a couple of folk known through him. It was and still is a horrific traumatic world changing event.
I don't have an issue with Op's confusion or asking, or how it was put.
From an engineering or emergency response angle etc, it was a very complicated event.
From a viewer perspective it was a horribly simple drawn out traumatic event.
What's below is the 'official what happened physically to the planes,' based on eye witness testimony, forensics, and salvage, confirming each other. It may help to understand each floor of the towers was roughly an acre.
The first plane sliced through damaging floors 93 to 99 of the North Tower, and lodged in the building. A landing gear wheel from the plane went clean through and landed a few blocks away.
Inside a fireball of jet fuel exploded on impact, shooting down one, possibly more, of the lift shafts. That fireball exploded onto several lower floors. (Proven are 77, 22; the West Street lobby; and B4, four stories underground.) A large part of the plane was witnessed to be whole, post impact, inside the building, burning fiercely, by people evacuating from 105 in the South tower.
Flight 11's defibrillator was found blocks away in 2014.
The second plane banked as it hit the South Tower cutting through and damaging the 77th to 85th floors. Because it banked, it left parts of those floors (notably staircase A) mainly intact. This is why we have a handful of impact zone and above survivors and eye witnesses to the condition of the first plane in the North tower, post impact, viewed from the South tower.
In the South tower only eighteen people from the impact zone or above survived after the plane hit. One person survived from the center of the impact zone on the 81st floor. The planes wing sliced through his office. His description was of total “demolition” and everything “broken up.” He struggled to breathe from the strength of the jet fuel. Parts of the 2nd plane went straight through the building and landed a few blocks away on three separate sites.
Because staircase A survived, there are witnesses from the 105th floor who reported seeing part of the fuselage of the plane lodged in the north towers while they were evacuating, before the 2nd plane had hit the south tower. They had made it to a few floors below where the second plane impacted and experienced a fireball shoot down the stairwell.
A wing attachment found years later could have come from either plane.
It is likely the first plane was mainly intact post impact but subsequently burnt up and the second plane broke up considerably more on impact before what remained inside the building burnt up. Some un-burnt parts went through the building entirely. Some burnt plane parts were effectively ejected from the buildings during collapse.
What happened to bodies and why, is also what causes some of the confusion.
There's enough info there for you to find more with proper sources and detail.
The only stupid question is the one you don't ask. How, where, and when you ask it, is a skill you will develop. Good luck with your course.