Distinction Between the Tax Payer ID Field and the Tax Registration Field - R11.5.10

Can someone provide me the distiction between these two fields?  The Tax Payer ID is = Employee SS# and/or FED ID# (business)?  Does the 1099 report pull from the tax payer ID #?  What is the Tax registration field?

Please advise as client is working on a tax project.  Client is on R11.5.10 and NOT using E-Bus Tax.

Thank you,

Stacy