Is a misdeed that which is committed against people, and a sin that which is committed against Allah?

No distinction has been made between "dhanb" (sin) and "sayyi'ah" (evil deed), and it appears that such a distinction is not accurate. Indeed, "sayyi'ah" may be used to refer to polytheism (shirk), as in the Almighty's saying: "Yes, whoever earns an evil deed and is encompassed by his sin - those are the companions of the Fire; they will abide eternally therein." Similarly, "dhanb" (sin) is used to refer to matters related to the rights of Allah and the rights of people, as in the Prophet's (peace be upon him) statement regarding the greatest sins: "That you ascribe a rival to Allah while He created you," and "That you kill your child for fear that he might eat with you," and "That you commit adultery with your neighbor's wife."