Comment by arghwhat

Closed loop is the control method, "servo" describes an assembly of a servo motor and its controls.

Good closed loop stepper controllers are a huge step up (heh) from open loop control, but there's a big difference in characteristics of a stepper motor - which is a very special motor configuration making huge trade-offs specifically to allow repeatable open-loop operation - and the more standard servo motor choices. Because steppers are special you also tend to specifically say "closed loop stepper" rather than considering it a servo.

Be a bit careful with random closed loop controllers though. Cheap ones can be finicky, and poor tuning and broken failure modes is no fun when used in machinery that could injure you, which tends to be where such steppers are installed. Aggressive and erratic movement or randomly entering fault and powering down is quite a lot different from simply losing steps.