What is the difference between the narration of the Heroes of Olympus and Percy Jackson and the Olympians?

Percy Jackson and the Olympians

Percy Jackson and the Olympians series is narrated by the first person perspective of Percy Jackson, the series' protagonist. Here is an example from The Lightning Thief: Chiron was waiting for us in his wheelchair. Next to him stood the surfer dude I'd seen when I was recovering in the sick room. According to Grover, the guy was the camp's head of security. He supposedly had eyes all over his body so he could never be surprised. Today, though, he was wearing a chauffeur's uniform, so I could only see extra peepers on his hands, face and neck. "This is Argus," Chiron told me. "He will drive you into the city, and, er, well, keep an eye on things."

I heard footsteps behind us.

This series adopts a third person, limited point of view i.e. only one person's thoughts are divulged at one time. Also, this series is narrated by three different character's point of view: Jason Grace, Piper McLean and Leo Valdez in The Lost Hero ; Percy Jackson, Frank Zhang and Hazel Levesque in The Son of Neptune.

Here is an example from The Son of Neptune:

The god's wrists were shackled in icy manacles, with chains that ran straight into the glacier floor. His feet were bare, shackled around the ankles and also chained.

"It's Cupid," Frank said.

"A really buff Cupid," Percy agreed.

"You compliment me," Thanatos said. His voice was as gorgeous as he was-deep and melodious. "I am frequently mistaken for the god of love. Death has more in common with Love than you might imagine. But I am Death. I assure you."

Hazel didn't doubt it. She felt as if she were made of ashes. Any second, she might crumble and be sucked into the vacuum. She doubted Thanatos even needed to touch her to kil her. He could simply tel her to die. She would keel over on the spot, her soul obeying that beautiful voice and those kind eyes.

"We're-we're here to save you," she managed. "Where's Alcyoneus?"