Yes, perhaps there is a different perception. To me and I think to other Americans, being a Nationalist means that we would always put America first in all things that required same, including trade.
American patriotism, to me anyway, includes a sense of Nationalism. It's a good thing.
If you think of nationalism as a synonym for patriotism then for me that's just a selfunderstanding way of feeling responsible for your compatriotes and pride on achieved things.
Over here in germany the word nationalism is used in a very different and negative way and is not the same as patriotism (we had a national -sozialistic party once - didn't make to good experiences with that word).
Btw beeing liberal over here means to be pro free market and a less regulated society. I understand that in the US beeing liberal means quite the opposite.
Best regards from the home of soccer.