My sister hates her drawings being criticised?

Both are incredibly good. Whether one is better than the other depends upon the viewer. You should consider sending them to publishers for use as Graphics in books.

It might become a lucrative career. To answer your question, the older one has less detail than the newer one. It is more abstract so it leaves more to the viewers imagination to fill in, making it personal to the viewer.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.