What's the difference between serial and CPSID?

CPS
1

What’s the difference between the below two methods:

1.use year, month, serial to identify and match household

2.use CPSID to identify and match household.

Thanks much!

2

The difference primarily rests between within-sample and across-sample uniqueness. The combination of YEAR, MONTH, and SERIALprovides a within-sample unique ID for each household.The CPSID variable, on the other hand, provides an ID that uniquely identifies households across CPS basic monthly samples. More detailed documentation about the creation and use of the CPSID variable is available here.