Empire Builders
While the Spanish Empire was developed in South American and the Ottoman Empire grew up from contiguous land conquests, the motivation for the construction of both empires included desire for power and prestige, while both entailed significant Islamic histories.
In earlier centuries, the Islamic Moors overran Spain and the Iberian Peninsula, establishing a Muslim government. This invasive force held power for a time thereafter, though Islamic influence was later removed through the alliance of Catholic Spanish regional lords through the marriage of Ferdinand and Isabella, the supporters of Columbus' later voyage to the New World.
The Ottoman Empire emerged from the pieces of the Abbasid Empire and the Islamic Baghdad Caliphate, conquered by Attaturk. While the Ottoman Empire was engineered to be secular and tolerant of religions, it was created with significant Muslim influence in history, culture, and government.
Spain sought prestige among its Western Europeans rivals, and the popular ticket to power in Europe after Columbus' discovery of the Americas was to conquer and establish mercantile ties with the new American territories. Economically, the gold and natural resources of the Americas brought to Spain were a mixed blessing. The new resources ensured strength economically at first, but later led to major inflation in other parts of Europe, called the Price Revolution. Politically this resulted in the eventual shame and loss of the Spanish colonies, but for the majority of the period between 1450 and 1800 Spain was considered a major power broker, splitting the Americas on a North-South line with Portugal at the Treaty of Tordesalles.
The Ottoman Empire was primarily focused internally, developing great economic strength through sciences, arts, and architecture. Socially, the Ottoman Empire was far more progressive than its Spanish counterpart - Spain endured severe Catholic influences and the infamous Inquisition, while the Ottoman Empire reinforced secular tolerance and increased religious freedoms. Overseas, the Spanish conquistadors decimated local populations and enslaved them to the mercantile agreement with Spain, while the Ottoman Empire focused on unification and control, incorporating new additions into existing components of the empire's holdings.
Politically, the Ottoman Empire was more internally aggressive, while Spain was focused on external one-upmanship with its European peers. Socially, the Ottoman Empire was more tolerant and culturally-developed than the Catholic overtones of Spain. Economically, Spain was initially far superior through mercantile trade, but eventually fell from that height; the Ottomans didn't progress quickly economically, but the Ottoman Empire was more stable economically.
One great advantage of the Ottomans in empire acquisition was the tolerance and comparative gentleness exercised towards conquered peoples. Through direct incorporation, the Ottoman Empire immediately gained social and economic resources while maintaining a stable local political environment. Spain, on the other hand, hired conquistadors to murder and enslave the local populations, instilling fear and hopelessness in all who were spared. This vastly reduced the economic, social, and political potential of the interaction by destroying social and political structures, creating confusion and disarray, and ruining any economic benefit the Spanish conquerors may have received from willing partners or established economic systems.
Citation
Eckert, Daniel C. The Empire Builders. (2007, November).