Christopher Columbus and Alvez Nunez Cabeza de Vaca were both explorers for Spain, but under different rulers and different times. The more famous, Christopher Columbus, came before de Vaca's time. Columbus sailed a series of four voyages between 1492 and 1504 in search for a route to Asia which led accidentally to his discovery of new land inhabited with Indians. Christopher sailed under the Spanish monarchs, Ferdinand and Isabella for his journey to the "Indies," whom he was loyal to by claiming everything in their name. De Vaca, followed in Christopher's footsteps and journeyed to Hispanionola for Spain's emperor, Charles V, the grandson of Ferdinand and Isabella. Both, Columbus and de Vaca composed a series of letters addressing the main issue of their journey to the new land, but both were expressed in a different manner, included different material, and were motivated to write for dissimilar reasons.

Columbus' and de Vaca's purposes to compose letters are quite divergent. Christopher Columbus' main objective in his Letter to Ferdinand and Isabella Regarding the Fourth Voyage, was to list his unnoticed accomplishments, justly sufferings, and devotion in order for the monarchs to save him. He had his heart set on Ferdinand and Isabella's pity to obtain their permission to go to Rome and other places of pilgrimage. In Columbus' "Letter to Ferdinand and Isabella Regarding the Fourth Voyage," Columbus had the intention to please his majesty by claiming his "[pure devotion which [he] has ever borne to the service of [his] Highnesses." He also states that the purpose of his expedition was not for his own good, and that "[he] did not sail upon this voyage to gain honor or wealth," but for his "true devotion and ready zeal" to serve his Highnesses. During his fourth voyage, Christopher endured many hazards, like imprisonment, which triggered him to compose a letter filled with his many accomplishments that he believes went unnoticed.

Columbus had hopes that this will generate some sort of pity from the monarchs. Alvar Nunez Cabeza de Vaca wrote his letters for entirely different reasons. His sole purpose was to inform others (of his sufferings and his discoveries of the Native Americans). He also wanted to "justify his conclusions regarding Spanish policy and behavior in America" which is mainly addressed to Charles V.

De Vaca believes that "[his] only remaining duty is to transmit what [he] saw and heard in the nine years [he] wandered lost and miserable over many remote lands." Therefore, he conveys to Charles V the many incidents that occurred throughout his struggle for survival while in Texas. In De Vaca's opinion, he thinks that the information he is revealing will be useful to others and will be "of no trivial value for those who go in [his majesty's] name to subdue countries." The descriptions which Christopher Columbus and Alvez de Vaca reveal are entirely different. Columbus wrote information that was insignificant. His explanations are very vague and are only somewhat in depth when something interests him greatly, like his "discovery" of the beautiful Espanola. Columbus wrote about the Indians and their land as if they were "nothing of importance." The majority of his descriptions of explorations were about himself or based on himself.

On the other hand, Alvez de Vaca claims that he is telling the "truth" and are "strictly factual." De Vaca "remembers all the particulars," in other words, every significant detail. Alvez mentions both positive and negative qualities of his experiences. It seems as if he is attempting to prove to everyone that the Indians are good people (attempting to change their instilled views). Of the many aspects of the Native American's lives, de Vaca mentions: the different roles people play and the many Native customs. Some customs Alvez had the opportunity to experience were: deaths and funerals, marriages, starvation, the system of food, relationships with each other, and mainly the ways how to survive. His actual hand's-on experience enabled him to be very detailed in his narrative.

Another reason of his detailed composition was because unlike Columbus, he was interested in the people and the land.