I am using Census data from 2000 and ACS data from 2008 - 2012. I am using BPL (Birthplace) to learn about the birthplace of the cases per continent. Some of my frequencies are very different than some reported on a census report. When I asked the census researcher about it they said that they are analyzing POB (place of birth). I am assuming that the variable is the same but was renamed in the IPUMS data for some reason but wanted to verify that this is the case.
The IPUMS-USA variable BPL is a recoded version of the original census variable POB. Because BPL was created to harmonize place of birth throughout all of the data files in IPUMS-USA, the coding structure is unique to IPUMS-USA. POB and BPL do not always group countries in the same way, however, every POB code corresponds to one and only one BPL code. I recommend looking through the BPL comparability statement for more information specific to BPL. If you are interested in a specific year, I can provide a crosswalk between BPL and POB.
I hope this helps.