My friend brought a "Rosa De Reyes" cake to work and it was different from the Mardi Gras cakes we had received. She explained about her family's tradition with the cake (it was not related to Mardi Gras) and how it was a holiday tradition.
And here is a description from the web about the other differences:
In Mexico, as in many Latino countries and southwestern states, the cake is celebrated with families and friends only on Jan. 6 along with the gifting of toys to children. Whoever gets the baby Jesus trinket baked in the cake has to host a tamales party during the first week of February, which is “ El Dia de Candelaria,” a day of church-going and visiting family. Mexicans refer to the sweet cake as “Rosca de Reyes,” or King’s Cake. “Rosca” means wreath, and “Reyes” refers to kings. The Rosca de Reyes has an oval shape to symbolize a crown with dried and candied fruits to symbolize the many jewels that a crown would have. The trinket baked in the cake symbolizes the hiding of the infant Jesus from King Herod’s troops.
The most popular version of all King’s Cake celebration is held in New Orleans, where eating this sweet bun starts on Jan. 6 and continues through the Mardi Gras festivities ending with Fat Tuesday and, in some cases, longer. In fact, the King’s Cake with its purple, gold, and green frosting has become an essential iconic symbol for the Mardi Gras festivities and the city of New Orleans and as such has become a significant moneymaker now that the cake is eaten during other celebrations and events such as football (so much for tradition).
