Katharine McPhee and David Foster Disagree over Disciplining Son: 'His Era of Parenting Is Different' (Exclusive)

Katharine McPhee and husband David Foster know where they align and where they differ.

In the studio, recording tracks like those on their new updated album Christmas Songs, out now, they're perfectly in sync. "It's a pleasure," McPhee, 39, who's set to perform with her husband at this week's Macy's Thanksgiving Day Parade tells PEOPLE of singing along to Foster's music. "I just always lean into his expertise. It's always been an easy thing for me."

Asked about the times they don't see eye-to-eye, McPhee says it's usually when she's navigating the road. "That's less of a pleasure. He's always like 'Where do I turn now, where do I turn now," she says with a laugh. "The only time we get into arguments is when I'm helping him navigate freaking directions."

Adds Foster, "It's true. Because she's a backseat driver!" Says McPhee, "I'm not, I just know how to follow directions."

Getting around town isn't the couple's only point of contention. A more important disagreement surrounds their parenting styles and philosophies, a difference they both say relates to being from different generations.

"I want to start disciplining [Rennie] and Kat's not really down with that," Foster says of their 2-year-old son.

"No, that's not true," counters McPhee. "I just want to discipline in my own way. There's the more old-fashioned way of disciplining which involves time-outs and things like that. My take is that you can have more mindful parenting opposed to just assuming that a two or three-year-old can have time alone to reflect on what they've done poorly."

Continues McPhee, "I think the more new way of parenting is understanding that with a child, there's only so much that they can intellectually understand. Saying 'That was really bad, that was really, really bad,' gets into a shaming thing. I think disciplining is something that happens over time."

Foster, who's also dad to 5 adult children, doesn't fully subscribe to his wife's view on the matter. "David's more results-based. He's like, 'He can't just walk by and swat people'," says McPhee. "Of course not. But he's two and a half and he's learning those things."

She adds, "It's just a different approach. I think his era of parenting is different than mine." That said, "We don't have arguments about it," she adds.

McPhee's hope is that disciplining will be a team effort, and she's not rushing it. "They learn how to how to have personal space and all those things over time," she says. "They have to have experiences where they have negative reactions from people more than just their parents, from teachers and fellow students. They get to experience it with life. So we'll just wait. Talk to us when he's three."