Thomas Hobbes and John Locke had very different views of human nature. The basic difference between the two of them is that Hobbes had a rather negative view of human nature while Locke had a much more positive view of human nature.
You can see this difference in the kinds of political systems they each advocated. Hobbes, thought that only a monarch, a "leviathan" of a power, could keep people in check due to their inherent badness. By contrast, Locke thought that people were good enough to be able to govern themselves. He thought that the people were good enough that they would be able to set up representative governments that would maintain a stable society.
Hobbes viewed men as inherently selfish and greedy, who would constantly try to maximise their own power and wealth at the expense of others. As a result, individuals had to live in constant fear for their own physical safety and the security of their property. Thus, to minimise this fear, men had to agree to create and obey a higher and more powerful political authority, which was the state of "Leviathan".
Locke, on the other hand, argued that not all humans were bad and showed more faith in the innate human nature to be good by presenting the world as full of good-natured, well-mannered, compassionate and public-spirited people. There was, however, the presence of a few "bad apples" that could potentially ruin social order. While there was a need for individuals to enter into a "social contract" with the state, he argued that individuals should not surrender all their rights to the state, thus preventing the creation of a state with unlimited absolute power.