The Receive Mouse Moves tracks the mouse position in real time using the events from the Updated Window feedback cable but the Check Mouse Status node doesn’t work in the same way and needs the Fire on Display Refresh node to work.
These two nodes provide two different ways of getting information about the mouse — one of them firing events with each mouse move and the other synchronizing with the events from another source. Receive Mouse Moves is good if you want to drive some behavior (e.g. move an object onscreen) with mouse movements. Check Mouse Status is good if you only need to check the mouse position when something else happens.
If you inspect the two nodes closely, you can see the differences. Check Mouse Status has an event wall for incoming events from Window, but Receive Mouse Moves doesn’t. As the manual states, “If an event comes into a node only through an input port with a wall, then the event won’t go out any of the node’s output ports.”