Another difference that you fail to mention is that we (the US) have been meddling in Cuba's affairs for damn near 100 years, including dozens of documented attempts to assassinate their head of state. For some reason, Cubans find this behavior objectionable, and the idea of seized assets dating before most of them were born being the justification for this conduct is laughable.
God knows I'm not saying the Castros are happy little fuzzy angels who never did no wrong, but it's indisputable that they're a damn sight better than some of the thugs we happily deal with in the rest of the world. It's ridiculous and childish to blame everything on them, but it plays well in certain areas of south Florida which hold disproportionate power come election time.