How do you tell the difference between a nema 6-15 and 6-30 plug?

A NEMA 6-15 plug has a flat blade and a round blade, while a NEMA 6-30 plug has a flat blade and two round blades. The 6-15 plug is rated for 15 amps and 125 volts, while the 6-30 plug is rated for 30 amps and 250 volts. The 6-15 plug is typically used for small appliances, while the 6-30 plug is typically used for large appliances, such as air conditioners and refrigerators.