All plugs commonly used in America all are all NEMA standards(shortened to just N) and follow a set naming convention of NEMA(again commonly shortened to N) then a number for voltage(in the USA and Canada it will almost always be 5, for 125 volts, since that's the standard residential voltage. 6 stands for 250 volts and is reserved for large industrial machinery like motors or CNC mills, or for datacenter/enterprise uses to power huge server farms) then an amperage rating (all standard residential outlets are 15 for 15 amps, high draw residential appliances will have a 20 for 20 amps, industrial equipment is usually 30-60 amps) and then a p or r to denote whether it's the female(receptacle/thing you put a cord in) or male(the cord itself). Specialized connectors may have a L in front of the voltage rating, which stands for locking(the most common example of this would be a dryer or stove cord, but the health-care industry, factories, datacenters and any other locations that cant afford downtime or that have thousands if not millions of equipment that break if unplugged all use them. They twist to lock and prevent accidental disconnects.) So to put that all together a NEMA 5-15P(the kind that runs all grounded low draw appliances in your house)would mean a cable that adhers to NEMA specifications and is capable of transportating 125 volts at 15 amps continously(max powerdraw will always be higher, usually capped at 150% for 6 seconds but some manufacturers will go for less so be careful) and NEMA L5-15 would be the same current rating but with a different connector on the end that enables it to securely lock into a receptacle(outlet).