ARP Spoofing and ARP Poisoning are used to mean the same thing, which is altering address resolution protocol records. “Spoofing” means impersonating, so ARP spoofing means representing a computer with the IP address that was originally assigned to another computer’s MAC address. In the interest of thoroughness, this should also include altering the relevant ARP record. “Poisoning” means corrupting the ARP table. It is possible to implement spoofing without poisoning. However, this relies on the tricked computer not checking ARP tables, so it is better to implement poisoning as well.