The diplomatic crisis between Seoul and Tokyo deepened further Thursday as two South Korea courts ordered two Japanese firms to pay compensation to South Korean wartime laborers.

Experts and diplomats say there has been a huge gap in perception between the two nations over the labor issue, resulting in apparent confusion over the usage of relevant terms.

So, what are the outstanding issues involving wartime laborers, and where does the confusion lie over the usage of relevant terms? Below is a series of questions and answers regarding an issue that has rocked ties between the two Asian neighbors in recent weeks: