There is nationalism: "our people are cooler, let's favour them, maybe we'll make it harder for others but we don't care", so there are legit parties with that views: conservators, protectionists, socialists (I don't refer to specific parties or movements, just a general inclination). I don't like them that much, but we shouldn't judge opinions, it's better to promote our own.
And there's nazism, which usually refers to an ideology like Hitler's: "yes, we are better, so let's kill everyone else or make them slaves", this is just pure evil, I leave it unexplained because it's really obvious.
I don't think socialism is about favouring one type of people, the definition is the ideology that prefers social ownership of property instead of private ownership of property.
That said, (neo-)nazism and nationalism differ in that nazism is also accompanied by (pseudo-scientific) racism, social-darwinism, and anti-communism.
So if you believe that people that look like you belong to a different race that is superior to others, and is destined to overcome other races of people through struggle, and that your nation belongs to your race, and that the best form of government in that nation is a strong hierarchy where the best lead through power, you are quite nazi-like IMO.
Socialists definitely don't value one group over another, they value literally the entirety of humanity. Supporting the Proletariat over the Bourgeoisie is more about property relations and class abolition than literally valuing Proletarians over Bourgeois.