Short term foster care may be one night, a few days, weeks or months.
Long term foster care can be 6 months or years.
Permanent care is legally up to 18 years, but i would presume that you would then consider that child to be part of your family by then (we do!)
Adoption means the child is a legal dependent with all legal rights of a child born to you including being entitled to your estate.



Different departments may vary on definition, so you will have to check with your state department.