Wink, blink both mean to move one’s eyelids.
Wink usually means to close and open the eyelids rapidly and usually involuntarily or to close one eye part way mischievously or teasingly or as a hint or a command.
To blink is to wink involuntarily and with eyes nearly shut as if dazzled, partly blind, half asleep, or suddenly startled. In extended use wink implies connivance, and blink suggests evasion or shirking.