The legal separation is different from the dissolution of marriage case. It's really called an "Action for support" and "parent unconnected with the solution of marriage." The two are independent remedies. One would only seek the separate maintenance or the action for support unconnected with divorce. If the parties are going to be living separately, but do not want to dissolve the marriage. As to which is easier or less expensive, the answer is neither, and that they are very different. The determination of whether a dissolution of marriage should be filed or an action for support unconnected with divorce depends on the circumstances of the parties and whether they want to terminate the marriage.