There really is little commonality between the two cultures.
What commonalities do you think there are?
What commonalities do you think there are?
And HK culture is not mainland culture, though the party is trying to make it so. Not that there is a single mainland culture. Hokkien != Shanghainese != Beijing, etc.
If you strip things down to the rawest motivations, then sure everyone is similar. But all the details will look extremely different to most Americans, even CNY, filial piety, meals and family structure, etc.