Sometimes its pretty hard to tell, and sometimes it depends upon what kind of tortoise you're talking about. In desert tortoises, a wc tortoise with any age on it will have a very smooth and dinged up carapace, while that same age tortoise being captive bred will look more pristine, still have some color to the carapace and you would be able to see growth lines.
Generally speaking, a wc tortoise will look more smooth and perfect, while a cb tortoise will be ever so slightly ridged through the growth lines.
And most WC are full of parasites that can infect your others if you bring one home.
Some WC are illegal to own ...
So do your homework if getting new torts.
If you see a hatchling for sale, it's almost positive it is CB. If it's over 4 inches, it could be WC. The ones that have more scratched up shells are more likely WC.
CB torts can also have parasites, but less, and less commonly. I would want to have personal information on the tortoise and the seller to prove either way what you are getting.
What kind of tort are you interested in, and how do you plan to acquire it? Best wishes.
I was just curious. I have been reading people's interpretations of the various photos here on the forum, as to whether a tort is wc or cb. I rescued the Greek ibera I currently have. He was deemed as LTC WC. I am waiting to take a fecal to the vet to check for parasites. He is the only tort we have.