PETER RICE is a quick study. A mere eight weeks into his Fox Entertainment chairman gig, he’s already mastered the mantra that nothing can rival broadcasting’s unparalleled audience reach.

“Broadcast television still reigns supreme,” Rice told reporters during a conference call Monday.

Given that this is the major networks’ upfront presentations week, Rice is an understandable convert to this refrain — one designed to counter cable’s aggressive push, particularly by the Turner Entertainment Networks, to level the advertising playing field. Indeed, Turner has not only crashed the upfront party but had the temerity to prominently place ads that say, “Viewers don’t make the distinction between broadcast and cable.”

As is often the case with TV’s intramural skirmishes, the truth resides somewhere in between — though there’s no denying that broadcasters have lost much of what David Byrne might have called their “specialness.”

EVEN ON THEIR best days, with their strongest franchises, cable seldom matches ratings for mediocre network entries. As Rice noted, the 6.8 million people watching TNT’s “The Closer” — boffo by cable’s yardstick — would rank about 75th among major-network offerings.

At the same time, the networks are no longer automatically Gulliver to cable’s Lilliputians. Although cable doesn’t approach top-rated broadcast shows, on any given night one or two cable networks taken together approximate a broadcast audience — see TNT’s 8.4 million viewers for Sunday’s Boston-Orlando NBA playoff game — while concurrently, at least one broadcaster posts results anemic enough to resemble cable levels.

The sheer surface area that helped define broadcasting is also fast diminishing. Networks have long since turned Saturdays into Rerun Theater to lighten their programming costs. Now NBC will strip “The Jay Leno Show” weeknights, shrinking its programming profile even more.

Factoring in “Sunday Night Football,” Saturday rebroadcasts and Leno, only half of NBC’s 22 primetime hours this fall will be devoted to traditional series — including “Dateline” and a two-hour “The Biggest Loser.” At eight hours of scripted shows, suddenly there’s not such a gaping void between NBC’s programming portfolio and the footprint of baby sister USA or TNT.

The situation is blurred further when broadcasters and cable engage in what has become an odd baton pass around Memorial Day. Network scripted series take a siesta, to be supplanted by unscripted fare like ABC’s “Wipeout” or NBC’s “I’m a Celebrity … Get Me Out of Here!” Cable, meanwhile, trots out splashy dramas as part of a one-time counter-punching tactic that has mushroomed into a full-scale assault.

The broadcasters have finally responded by scheduling a dollop of scripted entries during the summer, but most have a pervasive whiff of filler about them. Several, such as Fox’s “Mental” or NBC’s “The Listener,” are international acquisitions or co-productions obtained at bargain prices — placeholders meant to cultivate the illusion the webs haven’t hung out the “Gone fishin'” sign.

OF COURSE, the chest-thumping about cable’s collective and individual rating inroads should come with a lengthy disclaimer.

For starters, the finest series on basic and pay cable generally don’t draw significant audiences. Prestige shows like “Dexter,” “Damages” and “Mad Men” bathe their respective networks in a patina of quality, but if a broadcast network delivered those numbers, even now, those hours would be canceled before the second commercial break. Nevertheless, cable has been largely free to trumpet its successes without being subjected to a level of scrutiny commensurate to what broadcasters face regarding commercial misfires.

The space between them, however, continues eroding. Fox just renewed the Joss Whedon series “Dollhouse,” which would have been unthinkable as recently as 2005, when “Arrested Development” got axed despite averaging more viewers than the Eliza Dushku leer-fest.

Turner’s self-serving argument is intended to eradicate the ad premium that broadcasters historically enjoy, but that’s inside baseball. Practically speaking, viewers are too inundated with options to discriminate much based on dial position — rendering the broadcast-cable divide (including disparate content standards) increasingly arbitrary.

So while differences exist, the gap is clearly narrowing — but cablers should be careful what they wish for. Because my guess is if they ever get a taste of being graded by the exact same criteria as broadcasters, they suddenly won’t be quite so eager to completely erase those fading dotted lines.