Devil Fruits CAN take you to another level, but only with strong Haki.
This is why Luffy will be the Pirate King.
Gear 4 was notable because he was merging his Haki with his Devil Fruit's abilities to maximize his power. Gear 5 is the full realization of that: Luffy's Haki, his Will, has matched his Devil Fruit Abilities.
Kaido said Awakening is when your Body and Mind are able to fully harness your Ability.
Luffy was weak in the beginning because, even though he was strong, and was great with his Fruit, he didn't have the Haki. Now, he's mastering both his Haki and his Fruit. True top tier.
Gear 5 is CoA and CoC full coating combined with Awakening, after all:
That white around Luffy IS CoC and CoA coating... but, why is it white? It might have to do with some of the white lightning from Haki we see in other parts of the series, like when Law broke through Doc Q's disease.
Gear 4 is kind of a quasi Awakening, since it's Luffy doing full body CoA, but, Gear 5 is even more taxing, since Luffy is coating his whole body in CoC. This is why he's exhausted after using Gear 5, he's expanding a ridiculous amount of Haki to use it.
Shanks seems to be much more casual about his Haki usage if necessary, indicating he has way greater control/efficiency/storage space when it comes to Haki. Luffy never really got Gear 4 under control, either; after, he was always exhausted. True mastery will be Luffy using those forms for a bit without crashing right after, and, until he does that, guys like Shanks are a ways ahead of him, IMO.