Nate Berkus (Carter Berg)

What’s the difference between the NBC that is in first place during the season’s fourth quarter, and the fifth-place NBC during the first quarter?

One reality-competition series hit and one football show.

To address half that problem, NBC has stepped in where ABC has pulled its foot out. NBC has ordered the home-makeover competition series “Renovation Nation,” which will be hosted by interior designer/Oprah protege Nate Berkus. (Last season, ABC ended its entry in the genre: “Extreme Makeover: Home Edition.”)

Berkus was available because his syndicated show recently was canceled for lack of viewer interest. He had a much better run during his eight years as Oprah’s in-house design expert on her syndicated talk show.

Home-makeover series aren’t new to broadcast TV. ABC had a monster hit with “Extreme Makeover: Home Edition,” after network suits decided that slicing and dicing homes that needed an overhaul was a better business model than doing same to women’s faces (which was the subject of the network’s original “Extreme Makeover” franchise).

Each week on “EM:HE,” experts made over homes for some needy family — veterans, victims of natural disasters, the homeless, etc. — ending with much weeping and hugging, and feel-gooding. At its peak, during the 2004-05 TV season, the show clocked about 16 million viewers; by its final season, it was down to less than 6 mil.

NBC, however, believes it has cracked the code: Homes will not be re-made for some lucky family in need; instead, they’ll be re-made for lucky. . .viewers!

The home builders and designers, meanwhile, will be competing for “a huge cash prize” and for the honor of being crowned something or another — NBC had not yet come up with a zippy, “American Idol”-esque title at press time.

Throughout the season, viewers can tour the homes virtually — and buy stuff!

And to make sure you tune in, weekly prizes will be given away to viewers, ranging from luxury household items to home makeovers — and cold hard cash!

“We believe we are in a time where Americans want to feel empowered and inspired to make changes to their homes; changes that will not only increase their value and quality of life, but at the same time — not break the bank, ” NBC reality-TV guru Paul Telegdy explained in Monday’s announcement.