What's the difference between patriotism and nationalism? Here's some of what George Orwell had to say about the distinction in his 1945 essay, "Notes on Nationalism."
"Nationalism is not to be confused with patriotism. Both words are normally used in so vague a way that any definition is liable to be challenged, but one must draw a distinction between them, since two different and even opposing ideas are involved. By ‘patriotism’ I mean devotion to a particular place and a particular way of life, which one believes to be the best in the world but has no wish to force on other people. Patriotism is of its nature defensive, both militarily and culturally. Nationalism, on the other hand, is inseparable from the desire for power. The abiding purpose of every nationalist is to secure more power and more prestige, not for himself but for the nation or other unit in which he has chosen to sink his own individuality.
"So long as it is applied merely to the more notorious and identifiable nationalist movements in Germany, Japan, and other countries, all this is obvious enough. Confronted with a phenomenon like Nazism, which we can observe from the outside, nearly all of us would say much the same things about it. But here I must repeat what I said above, that I am only using the word ‘nationalism’ for lack of a better. Nationalism, in the extended sense in which I am using the word, includes such movements and tendencies as Communism, political Catholicism, Zionism, Antisemitism, Trotskyism and Pacifism. It does not necessarily mean loyalty to a government or a country, still less to one's own country, and it is not even strictly necessary that the units in which it deals should actually exist. To name a few obvious examples, Jewry, Islam, Christendom, the Proletariat and the White Race are all of them objects of passionate nationalistic feeling: but their existence can be seriously questioned, and there is no definition of any one of them that would be universally accepted.
"It is also worth emphasising once again that nationalist feeling can be purely negative. ... When one grasps the implications of this, the nature of what I mean by nationalism becomes a good deal clearer. A nationalist is one who thinks solely, or mainly, in terms of competitive prestige. He may be a positive or a negative nationalist — that is, he may use his mental energy either in boosting or in denigrating — but at any rate his thoughts always turn on victories, defeats, triumphs and humiliations. He sees history, especially contemporary history, as the endless rise and decline of great power units, and every event that happens seems to him a demonstration that his own side is on the upgrade and some hated rival is on the downgrade. But finally, it is important not to confuse nationalism with mere worship of success. The nationalist does not go on the principle of simply ganging up with the strongest side. On the contrary, having picked his side, he persuades himself that it is the strongest, and is able to stick to his belief even when the facts are overwhelmingly against him. Nationalism is power-hunger tempered by self-deception. Every nationalist is capable of the most flagrant dishonesty, but he is also — since he is conscious of serving something bigger than himself — unshakeably certain of being in the right. ...
"It can be plausibly argued, for instance — it is even possibly true — that patriotism is an inoculation against nationalism ..."