The similarity between the methods that Cavour and Bismarck used in their attempts to unify their respective nations can be summed up in their employment of the concepts of realpolitik, war, and diplomatic manipulation.

Both men were strong nationalists and monarchists, but that seems to be where their ideals ended. They did not shy away from lying and cheating to achieve their goals. In their efforts to unite their nations, they focused on "practical" matters, even if many would find their actions immoral. To Cavour and Bismarck, the ends justified the means.

For instance, Cavour knew that he could not achieve his goals without outside help from a strong foreign power. Napoleon III seemed like a good potential ally for him. Cavour secretly negotiated an alliance with the French and then instigated a fight between Sardinia and Austria to get them involved. Following this short war, Sardinia and Lombardy were joined. Later, Cavour organized votes in other Italian lands his army had occupied, against the wishes of Garibaldi, in which Italians voted to join Sardinia.

Bismarck also used deceit to achieve his ends. Like Cavour, he goaded Austria into attacking his country. Austria's defeat resulted in the end of the old German confederation. Bismarck was then able to form a new confederation of northern German states, with Prussia at its head. In order to get the southern German states on board, Bismarck instigated a war with France. The southern German states, therefore, had little choice but to join the new German confederation for their own protection.

As you can see, both Cavour and Bismarck attained their goals by tricking their neighbors into starting wars and making beneficial, if manipulative, diplomatic alliances.

Otto von Bismarck and Camillo Benso, Count of Cavour were influential in the unification of their countries. Bismarck helped unite Germany while Cavour helped unite Italy. Both men used various methods to achieve unification.

Otto von Bismarck wanted to unite the German states into one country with Prussia in the lead. Bismarck used wars against Denmark, Austria, and France to help unite the German states into one country. As a result of defeating Denmark and France, Germany gained land. By defeating Austria, Prussia would be the leading state in pushing for the unification of the German states.

Cavour was more supportive of diplomacy than of confrontation to achieve the unification of Italy. However, there were some wars that were fought to enable the Italian states to unify. He worked closely with Napoleon to make agreements that would lead to a war with Austria. With Napoleon’s support, Cavour was successful. After a series of other events, Italy was eventually unified. Cavour used negotiation and some military action to accomplish his goal of unifying the Italian states.

In their efforts to unify Germany and Italy, Bismarck and Cavour mutually employed Realpolitik. This was a political tactic characterized by the employment of practical, even when unethical and unprincipled diplomatic and warring tactics to attain goals of national interest, such as unification.

In Germany, Bismarck carefully initiated an alliance with Austria to defeat Denmark during the Danish war that took place from 1864 to 1865. Bismarck cunningly isolated Austria from Russia and France and convinced these two states to remain neutral. Soon after this, he sent his army into Holstein, an Austrian territory, thus provoking Austria into war, which the already weakened Austria lost. Finally after consolidating support from German allies, he instigated political tension between France and Prussia causing France to declare war on Prussia. Due to the support Prussia had, France was defeated.

In Italy, Cavour strategically contributed to the consolidation of Sardinia, then created an alliance with France to fight with Austria in order to acquire Lombardy. Later, he managed to convince Austria to attack Sardinia. He manipulated international events in order to get sympathy from other countries and to get military support in order to be able to act to his advantage.

In summary, both men used diplomacy and military action to attain unification, but they differed in which tactic dominated their unification efforts. While Bismark was not hesitant to engage in direct warfare, Cavour either supported (Crimea) or instigated (France) military action between other nations. Both men had their focus on unification and both put goals and action ahead of ethics and principle, but Bismark favored direct engagement in war while Cavour favored diplomatically manipulating others in their military engagements. 

Although Bismarck and Cavour had similar goals (to unify their respective countries) they pursued their goals in relatively dissimilar ways.  Bismarck used aggression and force, while Cavour used diplomacy and moderation.

Cavour's state of Piedmont was not really in a situation where it could unify Italy by force.  Therefore, Cavour had to find other ways to unify Italy.  Mainly, Cavour did this by making political deals with other, stronger countries.  For example, he used diplomacy to get Napoleon III of France to support his aims.

By contrast, Bismarck's Prussia was strong enough to use war to unify Germany.  Bismarck was able to use war to force other German states to unite with Prussia.  Finally, he was able to fight France to get the last parts of what he felt should be Germany.

The different situations of Italy and Germany, then, forced these two leaders to use different methods to unify their countries.