Quite a few ponies, including Lemon Drop and Bow Tie, had both multiple releases as well as very wide releases across the world. Because of that there are sometimes deliberate minor differences in their releases but there are also batch differences which come down to the sheer quantities of ponies produced across different years. And finally there is of course environmental differences due to sun and what the pony has been exposed to over the years.
If you have pictures of the ponies we would be able to perhaps tell you with more certainty what it is.