I have very little experience in telling a feral from a stray other than what I've seen...
A stray is usually a former house pet whose interaction with humans has been decent. Ferals have not ever interacted with humans, or have reverted to the wild animal behavior that is instinctual to them.
One thing I've noticed with strays is that they're willing to come up and be petted within a short time of you feeding them and/or being seen by them (short being relative), whereas ferals hide away, or will only eat food if you're not present.
A great example is the difference between Charlotte and Penguin.
Charlotte would be willing to eat with me sitting on the porch, stroking her while she ate. Eventually she would allow me to lift her to my lap, and scratch her ears and chin. Finally, one night, she walked in my back door, and hasn't left since.
Pengy, on the other hand, I'd fed for nearly a year before deciding to trap her. She took an entire month to trap, and she came in my house a year ago. Only now is she letting me anywhere near her, and I consider that gigantic progress.
That's the best example of a stray v. feral that I can think of...
As for the articles and posts here, MA and Anne know their beans. They've helped me (and I'm sure many others) learn more about the wonderful furrbottoms we share our lives with...and they know their cleaning remedies! LOL
Best of luck -