Hazelnut is indeed the fruit of a plant, belonging to nuts, but I have never seen or tasted hazelnut fruit alone. So I'm not sure if it smells like hazelnuts!
Irish is really full of cream! I feel a little more foam and the cream is more obvious. As far as I know, the quality of the cream used in Vietnam may be really good imported cream. Because some other brands of instant cappuccino on the market look like the taste of cream is really different!
As for mocha, I can't say it has any special fragrance and taste, but it's a little different from hazelnut.
Anyway, Vietnamese coffee has always been a culture. For example, Vietnamese iced coffee and shit coffee that everyone thinks can't be eaten.