For the saffron mashed sweet potatoes are tye "sweet potatoes or yams"?

Recently in H Mart (a chain of huge and wonderful Asian supermarkets), I looked at the yams. They had several types, They were huge and ugly, not what most supermarkets would sell as yams. Wssmom clearly tells the story.

According to Texas A&M: "Several decades ago when orange flesh sweet potatoes were introduced in the southern United States producers and shippers desired to distinguish them from the more traditional white flesh types. The African word "nyami" referring to the starchy, edible root of the Dioscorea genus of plants was adopted in its English form, "yam". Yams in the U.S. are actually sweet potatoes with relatively moist texture and orange flesh. Although the terms are generally used interchangeably, the U.S. Department of Agriculture requires that the label "yam" always be accompanied by "sweet potato."

Here's a link to find out more: http://aggie-horticulture.tamu.edu/archives/parsons/vegetables/sweetpotato.html?pagewanted=all

Judging by the use of saffron, I have to guess they're orange sweet potatoes due to the right amount of sweetness, but I think a yam would sub in fine. White or yellow sweet potatoes, however, probably won't work very well here