The Rambam, in his Iggeres Hashemad, outlines the parameters of kiddush and chillul Hashem. Here is a summary of his words that I think are relevant to your question:
Chillul Hashem, in its varying degrees:
1) One who does an aveira just in order to show his lack of respect towards the Torah.
2) One who acts in a way that appears as though he is doing an aveira, causing rumors to generate that he has no concern for halacha.
3) One who does something completely mutar but due to his stature people expect a higher standard. Example brought from the gemara is a rabbi who purchases meat on credit. Obviously cultural norms should be taken into consideration here.
4) One who has the reputation of being a chacham who acts in a way that makes people dislike him or lose respect for him, such as losing his temper etc.
In contrast, Kiddush Hashem:
1) One who performs a mitzva with no motive other than love for Hashem.
2) One whom “good things are heard about him”.
3) A person of stature who abstains from things the general public views as repulsive, even though he himself does not see things this way.
The Rambam also discusses other things which fall under the definition of kiddush and chillul Hashem, such as allowing oneself to be killed in certain instances rather than do an aveira, but I am assuming that was not the question here.