Are Yumen and Yumenguan the same place?

No. According to Baidu map query, Yumen is located in the northwest of Gansu Province, at the western end of the Yumen Pass Hexi Corridor, and on the south bank of the Shule River, so Yumen and Yumen Pass are not the same place. Yumen City, a county-level city under the jurisdiction of Jiuquan City, Gansu Province, the Republic of China, Yumen Pass was first placed when Emperor Wu of the Han Dynasty opened the road to the Western Regions and established the four counties of Hexi. It was named because jade was imported from the Western Regions through here.