What is the difference between IR-droop, voltage droop, and voltage fluctuation?

Hi,

What is the difference between IR-droop, voltage droop, and voltage fluctuation? Are they exactly same?

simple ohms law stats that V=IR
whenever current passes throughout any resistor, some voltage drops there .
voltage drop can be found by V= i X r.

now the answer of your question.
voltage droop and ir droop are same things.
if voltages are varying around the set point we use a term FLUCTUATION.
so ir-droop and voltage droop are equal but fluctuation is a different thing

Voltage drop and IR drop is same.

Whenever current passes through a resistance of some kind, a voltage drop occurs across that resistance. The amount of the drop is given by Ohm's Law:

V=IR
Where:

V = The value of the voltage drop

I = The current through the circuit in amperes

R = The total resistance of the circuit

Voltage fluctuations are changes or swings in the steady-state voltage above or below the designated input range for a piece of equipment. Fluctuations include both sags and swells.
Voltage fluctuation

Causes: Large equipment start-up or shutdown; sudden change in load; improper wiring; or grounding; utility protection devices

Vulnerable equipment: Computers; fax machines; variable frequency drives; CNC machines; extruders; motors

Effects: Data errors; memory loss; equipment shutdown; flickering lights; motors stalling/stopping; reduced motor life

Solutions: Verify proper electrical connections and wiring; relocate equipment; reduce voltage motor starters; uninterruptible power supply; voltage ride-through equipment.