To discuss the difference between A shares and Hong Kong stocks, we can start with the essence, trading rules and delivery system. First of all, from the perspective of stock types, Hong Kong stocks include blue chips, state-owned enterprises and red chips, while A shares are ordinary RMB stocks, focusing on the stocks of domestic listed companies.

In terms of trading rules, the characteristic of Hong Kong stocks is that they use "price" trading, and the price changes are carried out at the specified minimum range, which is related to the price range of the stocks. For example, for stocks with a price of HK$ .1-.25, the minimum price change is HK$ .1. The trading unit of A-shares is "shares", with 1 shares as the first hand, and the purchase needs to be an integer multiple. Zero shares can only be sold, but not bought. In the delivery system, Hong Kong stocks are delivered on T+2 days, that is, the settlement is completed on the second working day after the transaction is completed, while A shares are delivered on T+1 days, that is, the settlement is completed on the same day or the next day.

Generally speaking, there are differences between A shares and Hong Kong stocks in stock types, trading rules and delivery time. Investors should understand and adapt to these differences according to their own investment strategies and market environment when choosing investments. The above information refers to Baidu Encyclopedia's explanation of Hong Kong stocks and A shares.