Two discrete event simulation tools, GPSS and ARENA. Contrast these two. Where are they different and where are they very similar?

• 2个离散事件仿真工具，GPSS和ARENA。对比他们，找出他们的区别于相似处？老师给的考试样题，我觉得可能需要从一些方面开始分析，很困惑！