How can you tell the difference?
What makes you think there is a difference?
מ'האט אויפגעהערט עסן כשר, און אנגעהויבן עסן הכשרים
(no specifics intended).
However, I would speculate that the reason they chose one over the other is the availability of meat products.
It could become interesting (or disgusting, depending on your perspective).