There is no difference in functionality between the Philips upper arm blood pressure monitor and the Philips wrist blood pressure monitor. The screen of the Philips upper arm blood pressure monitor is a little larger, but the Philips wrist blood pressure monitor is more compact and makes a good travel companion. Some people can't have their blood pressure measured on their upper arms, due to the size of their arm, or because they perceive upper arm blood pressure measurement as painful. In these cases, measuring blood pressure at the wrist is a good alternative. To ensure accuracy, it is important to use the device exactly as directed in the instructions for use.