Difference between Stray and Feral Cat

Feral cat - a boy cat and it shows - photo by Wabana
The difference between stray and feral cat is that the stray cat is a domesticated cat that has strayed from its home. The cat is at the first stage of being feral. It is pre-feral. Its offspring will be feral if they are born outside of a permanent human home, meaning on the street or in the woods etc. Feral cats are domestic cats that are evolving back to wildcats but they are ill equipped to survive outside the human environment because of thousands of years of domestication.
The feral cat's life is considerably shorter than a domestic cat's life and a permanent indoor cat's life is potentially the longest of all because it is the most protected (but stress brought on by the unnatural environment may reduce lifespan).
The feral cat might live 3 years, while the domestic cat should live 15+ although purebreds live shorter on average (say 11). The true wildcat will live a decent length of time, say 11 years or so because despite the harsher lifestyle they are well able to cope.
Feral cats are often quite a mess health wise, being caught up in territorial fights and getting ill. Domestic cats are protected from this and receive medical care (usually). See damaged cat ears. I feed two stray cats and my companion cat was a stray. The 2 cats that I feed are quite well but one, the male gets hurt in fights requiring veterinary treatment because his injuries turn to abscesses.
Photo:
Comments
I have seen 100% ferals "coming from the cold" and re-adopt in time. It is cat nature to want to sleep close to other animals (which means you).
You don't really give enough information to really help us help you. Do you have young kids, does she go outside, is your home noisy, was it a mixed dog and cat breeder ... very possibly the "kennel" (cattery) was traumatic for her.