Nationalism and Patriotism are two closely related terms, with subtle, but meaningful differences. To have nationalism or patriotism means that one is loyal and devoted to their nation and has national spirit. Patriotism is even listed as a synonym to nationalism, which highlights the close relation of the two. Nationalism, however, has more force attached to its meaning.
Being patriotic could be compared with being a fan of a sports team; you love your team, you are loyal and devoted to it, and you would defend it. Being nationalistic, you still display all the love and devotion for your team that you do when being patriotic, but it entails a little bit more. When you display nationalism, you are more than a fan. You identify with your team, almost as if you were a member yourself. You’re not a fan of the Yankees, you are a Yankee. Such strong identification with a nation creates a deeper sense of devotion, love, and support within the individual, and is where the main separation between nationalism and patriotism can be found. Nationalism could almost be considered an extreme case of patriotism.