The difference between automatic and semi-automatic blood pressure monitors lies in the way air is pumped into and released from the cuff.
An automatic blood pressure monitor fully automates the process of measuring blood pressure. When using such a device, you just need to put the cuff on your arm and press a button. The monitor automatically inflates the cuff to the required level and then deflates it automatically after the measurement is completed. Many modern automatic blood pressure monitors are equipped with an "artificial intelligence" function, which accurately determines the required pressure, optimizing the process of inflation and deflation.
In a semi-automatic blood pressure monitor, part of the process is done manually. The user needs to manually inflate the cuff using a rubber bulb. After reaching the required pressure level, the measurement is performed automatically, but deflating the air from the cuff must be done manually through a special valve. This approach requires more effort and control from the user, but semi-automatic monitors are usually less expensive than automatic ones.
Thus, automatic blood pressure monitors offer greater comfort and ease of use, while semi-automatic ones require more active user involvement in the measurement process.