In general, there are two legal proceedings which can terminate your marriage: a divorce or a dissolution.
Both a divorce and a dissolution end with a court order dividing your assets, determining support, and allocating parental rights. Legally, the end result has the exact same effect.
There is only one difference between a divorce and a dissolution. In a dissolution, you and your spouse will have agreed to every term of your separation (ie. asset division, support, and child-related issues) before going to court. In a divorce, one or all of those terms will be contested and you are asking the court for help determining those issues.
It is important to note that even if you file a Complaint for a Divorce, that does not mean you can’t then settle the case by agreement the very next day, the next month, or even two years into an ugly fight. All it means is that you started the case not in agreement. Nothing stops you from agreeing later.