In short, there is no accurate comparison here.
On the one hand, we have (fake leather) plastic-based vinyl seating options such as Leatherette, Vegan Leather, Faux Leather, among others. These products require fossil fuels, thus adding additional carbon load to the atmosphere, and are primarily made from environmentally toxic chemicals Polyvinyl Chloride and Polyurethane. These chemicals have been shown to pose severe threats to the environment and contribute to significant health risks in humans, such as cancer and respiratory issues.
On the other hand, we have natural Genuine Leather, which is recyclable, compostable, and biodegradable Leather is a by-product from the meat and dairy industries that uses leftover hides. Without leather, hundreds of thousands of hides would go to waste in landfills each year.