What is the difference between logical DRC and physical DRC? Still confused.

The easiest way is to think by stage. Logical DRC checks your design early, before place and route, looking at the netlist and connections, like floating pins or wrong connectivity. Physical DRC checks the real layout after routing, against the foundry rules, like minimum spacing and width between metal shapes. Same idea of catching mistakes, but logical is about the design being correct, and physical is about whether the layout can actually be built.