The merlin lacks both of these features. The kestrel is often seen hovering in stationary flight, using strong, rapid wingbeats. Merlins cannot hover in this manner. The differences between the merlin and peregrine are less numerous. The major difference is size.
Peregrines are much larger and have a bold black mustache mark.
Coloration can be quite similar, but the peregrine has longer primary feathers. When perched, the peregrine's wingtips extend just to or beyond the tip of the tail. Falcons tend not to build large stick nests, and the merlin is no exception. It prefers to use old nests of crows, ravens, and magpies. If no suitable old nests can be found, then the merlin will build a loose nest of sticks in a tree cavity, on a roof, on a cliff ledge, or occasionally on the ground.