Joint physical custody is the sharing of the children between the parties. Sole physical custody is whereby one party gets custody of the children for a significant period of time. You must be careful to clarify if you are discussing physical or legal custody.
While physical custody relates to where the children are staying, legal custody is the ability of the parties to make important decisions for the children (i.e. education, religion, medical, etc.).
Joint legal custody is where the parties both have decision-making authority and must agree with one another.
Sole legal custody is where one parent has the authority to make these decisions on their own.