Suffix Meanings on LPC1769FBD100 Microcontrollers from NXP

If try to order the LPC1769FBD100 microcontroller from NXP USA Inc. you will find that we show three different options.
LPC1769FBD100K
LPC1769FBD100/P1K
LPC1769FBD100,551 (now listed as discontinued at DigiKey)

What is the difference between these options? According to the manufacturer’s forum the only difference between these parts is the packaging they come to us in.