Child visitation refers to parenting time. That is, the amount of time one parent spends with a child. When one speaks of a child visitation schedule or arrangement, they are referring to what days, times, and with what frequency a parent is going to spend with a child.
Child Custody can really be broken down into two different types: "legal" custody, and "physical" custody.
Legal Custody vs. Physical Custody:
Legal custody refers to the right of a parent to make decisions regarding a child's health, education, and welfare. For example, decisions about what school a child will attend, what doctors/dentists/therapists/psychologists a child will see, what extracurricular activities a child will engage in, what religion a child will study and practice, etc.
Physical custody on the other hand refers to a parents right to have a child live with him or her.
Sole Custody vs. Joint Custody
Legal and physical custody can each further be broken down into two forms, either "sole," or "joint," custody. Some may have heard of terms like "primary custody" or "primary custodial parent." Terms like these are legal fallacies because they have no legal meaning or significance. Terms like these are usually used to make one parent feel better about not having "joint" legal, or "joint" physical, custody. However, in reality only "sole" or "joint" custody have any legal significance and therefore implications.
If one has "sole" legal custody, it means he or she can make unilateral decisions regarding the child's health, education, and welfare. If parents share "joint" legal custody, it means that they must confer with one another in making decisions regarding the health, education, and welfare of a child.
If one has "sole" physical custody of a child, it means that parent has a right to have the child live with them, and, sometimes more importantly, it also means that parent has the presumptive right to move away with a child. In other words, if a parent has sole physical custody of a child and wants to move to a different county/city/state, it is the other parent that bears the burden of presenting evidence of why the Court should not allow the parent with sole physical custody to take the child when they move. If on the other hand, parents share "joint" physical custody, it usually means the child spends relatively equal amounts of time with both parents; and if one parent wants to move and take the child with them, the parent requesting the move would bear the burden of presenting evidence to the Court as to why they should be allowed to take the child with them when they move.
Any combination of the above custody arrangements is possible. That is, one parent could have sole physical custody of the child/ren, yet share joint legal custody, or vice versa. It is important that parents work together to create a custody arrangement, and a visitation schedule, that best suits the needs of their child/ren and their family.