“connect_pg_net”和“connect_supply_net”区别？

wenfangsibao

connect_pg_net              Connects  power, ground, and tie-off pins to the specified power and ground nets.
connect_supply_net        Connects  the supply net to the specified supply ports and pins.


请问supply net 和 supply ports supply pins分别指什么呢？
supply net 和 power/ground nets 不是一回事吗？
supply ports and pins 和 power/ground pins 不一样吗？