This one is losing hair on his back and his skin is white. He lets me pet him, hold him. But he likes to spend a lot of time outdoors. I want him to become indoor only but I do not know what to foUsually a true feral you won't see, they are very shy and skittish of humans. If you are offering food, they may come around more. They tend to be a little rougher looking: skinny, dirty, males have big cheeks if not neutered, may have ear tips if TNR, very slow to trust humans (if ever). Some who have been fed before will be a little less leery of humans but it tends to be situational (where they have been fed in the past or similar looking humans).
Most stray cats you will see will either be younger, lost pets, abandoned pets or kittens of former pets. They tend to be a little more comfortable with humans or see humans as a food source. They could be in rougher shape then a true feral as they usually have less skill surviving.
Outdoor pet cats or cats with outdoor access will tend to be healthier looking in general. They may have varying comfort levels with people.
Is there a particular situation you have a question about?