People often times get the two confused.  There is a difference.

When an expectant mother voluntarily makes an adoption plan for her child, she gets to choose the adoptive family and the kind of ongoing relationship she wants to share with her child and their family.  She can be assured that the family she has chosen will be her child’s permanent family. 

Whereas when a child goes into foster care, the biological parent(s) usually do not get to decide who their foster parents are and the adoption plan is not voluntary.  It’s also possible for a child in foster care to have several foster families.