Joint custody refers to a joint parent agreement, which is an order that will define both the responsibilities and rights of each parent in regard to the child's general well-being. This includes decisions affecting education, health, and religion. These orders will typically include stipulations allowing for periodic review should the need arise and should also include a protocol for settling disputes between any parties involved. Joint custody doesn't specifically entail equal visitation time but does typically entail equal parental rights.
Sole custody, on the other hand, means one parent has the ability to act in solidarity in regards to the best interests of the child. All decision making regarding the child will be up to them, and they will not have to consult the other party. However, the other party may still have a visitation schedule. As well, the other party will be able to make day-to-day decisions regarding the child while the child is in their physical custody. They will also be able to have access to the child's school and medical records in most situations.