The difference between Hong Kong and the mainland is that books are not expressed in pure words, but mainly in numbers, with more emphasis on flexible use.

What you learned in Hong Kong is practical (this is my subjective opinion, not my professional opinion, so I can choose to ignore it).

In fact, primary schools in Hong Kong are not too difficult. The knowledge taught is the same as that in the mainland, and there is no comparability. Of course, some schools teach in English. Maybe English is your only difficulty.