Thats fine. Even someone who knows leather and why like car leather never ever scratches while others are not durable.
I did some research to find you some information about the leather. There are different types of leather that is used for furniture. This is one of the possibilities as to why you had problems with the furniture you purchased. The smooth leather that most easily scratches is called Aniline. There are three qualifications that you can read about in this link if you scroll down to #6 Leather Types and it goes over which type of leather is the most durable: http://www.ahfa.us/uploads/documents/leather_booklet.pdf
According to the information supplied in the above link the best type would be type P which is protected leather and most scratch resistant. It has a protective finish which makes it more durable. The type N is Nubuck which is a suede like fabric which requires the most care. If you go into the section of the Glossary, it does give a lot of information about what is done to the leather to make it most durable.
The leather you want for the least problems is a protected leather.
I hope this will help you with figuring out why you have had problems with the furniture. I am so sorry that you had to replace the furniture due to cuts and scratches. Joan
Thanks so much for the info and effort...
You are welcome! I hope the new furniture will be better. Joan