How to quickly distinguish PU leather from PVC leather?

The quick way to distinguish PU leather from PVC leather is as follows:
1. By observation: From the corner, the bottom of PU leather is much thicker than PVC leather.
2. By touch: PU leather feels softer, while PVC leather feels harder.
3. By smell: If burned with fire, the smell of PU leather is much lighter than that of PVC leather.