That just comparison from an example. Nothing confirms that it can use to compare.
Luffy get take over by Joy Boy is just headcanon. No evidence saying this.
Or has anything say "I really got possese this body" yet ? the answer is no.
If he is really Joy Boy no reason to say "
This is my peak" and "this awakening shall be my gear 5".
Luffy: This is my peak, this awakening shall be my Gear 5!!!
Joy Boy take over: This is my old power from 800 years ago, this awakening is called Gear 5!!!
Different