At first, you should know that Tie Guan Yin Oolong is made of tealeaves harvested from tea cultivar named Tie Guan Yin while Huang Jin Gui is Huang Jin Gui cultivar. The two cultivars both originated from Anxi, Fujian, China. Now, they are widely planted in Anxi as well as other Chinese tea producing areas. They both rank among the four most famous Anxi Oolong along with Ben Shan and Mao Xie. Tie Guan Yin cultivar belongs to shrub while Huang Jin Gui belongs to small tree(arbor). Huang Jin Gui usually sprouts in the Mid- April, the cultivar sprouting earliest in Anxi, every year, about 20 days earlier than Tie Guan Yin. Tie Guan Yin is commonly only used to make oolong tea while Huang Jin Gui is also used to make green tea and black tea except oolong tea.
You can easily find the difference between the fresh tealeaves of Huang Jin Gui and Tie Guan Yin.
Compare the brewed tealeaves. It is also obvious.
The first two photos are of Tie Guan Yin and the last is of Huang Jin Gui.
Tie Guan Yin Oolong (Iron Goddess): The dried tea is heavy in dark green. The taste is complex and thick. The brewed tealeaves is elastic, fat and bright.
Huang Jin Gui Oolong (Golden Osmanthus): The dried tea is light in yellowish green. When brewed, it smells like juicy peach or osmanthus flower. The brewed tealeaves are thin and long.
Anyway, the best way is to make comparison tasting for several time. You would know well about them.
A cross was mentioned between a Ti Kuan Yin cultivar and the Huang Jin Gui cultivar in the Linkedin group where the article was discussed. I think it was probably Huang Guan Yin(Gold Kuan Yin). the newest member of Fujian Oolong family, is a cross-bred/hybrid tea varietal developed by the Tea Research Institute, Fujian Academy of Agricultural in 1980s with an attempt to let it have the good qualities of both Tie Guan Yin and Huang Jin Gui. Huang Guan Yin(Yellow Goddess of Mercy) has been widely grown in the Wuyi and Anxi regions since 1990. Now, here i showed more photos of them for your reference: