Look at Graham Nash on the cover of his new record, "Earth and Sky" (Capitol SWAK 12014). His face is weather-beaten, intense. He's standing with a funky '50s Kodak, with the wind blowing meanly and his back to a precipice. One more stiff breeze, and he's in for a two-thousand foot drop.

Now look at Rodney Crowell on the cover of his new record, "But What Will The Neighbors Think" (Warner Bros. BSK 3407). He's clean shaven and smartly dressed; his smile is open, as is his collar. The neighbors will think, Nice Boy. But that thumb pick he's pointing shows he's ready for action.

The pictures tell the stories in the latest product by two singer-songwriters. One is hanging on to his career by some very thin air. And the other is, in his own words, "dressed up fit to kill." And on the way up.

The 38-year-old Nash and his famous cohorts, Stills and Crosby, planned a group effort to follow their 1977 platinum record. But old personality problems erupted, and Stephen Stills walked out. So would it be another Crosby-Nash collaboration? Nope, got too heavy for David Crosby. By default, Graham Nash was making his third solo album.

And it's not bad. Nash has been around long enough to know how to round up the usual suspects -- L.A. cowboys and studio superstars -- and give them workable arrangements. The problem is the songwriting. Maybe some tough changes Graham Nash has gone through have impaired his ability to construct tight melodies. But the Graham Nash who once topped Stills and Crosby (not Young) in the solo sweepstakes by virtue of simple tunes that matched his elfin, wistful voice? Not home. Instead, we get a rather pretentious fellow who talks solely in terms of myth and majic. He gives no details we can connect with. And his voice is frequently lost in a multi-instrument haze.

Of course, he has a message: Technology is bad; nukes are very bad. If the ironies of preaching against technology by way of a 24-track recording studio have occurred to Nash, we see no signs of it here. For all the mysterio-cosmic jeremiads and elemental buzzwording, there's not much thought or insight. There are some cheerful, though vague, love songs. And a finale, "Into the '80s," that rocks suitably. What Graham Nash looks for in the 80s, we learn, is survival.

Rodney Crowell also sings of the decade upon us. After some satiric phrasemaking that pretty much sums up these droll times, "Here Come The 80s" predicts we'll make it after all. Crowell can afford to be optimistic. He's young, married to Johnny Cash's daughter, has people taking his songs to Top 20 ("Voila, An American Dream," by the Dirt Band; "Leavin' Louisiana In The Broad Daylight," by Oak Ridge Boys), and now a second record of his own.

On "But What Will The Neighbors Think," his singing shows a control and passion he's never displayed before -- not on his first record or his work with Emmylou Harris' Hot Band. It's a voice with a clear country timbre that can go from amiable to raucous in a drop of a quarter note. And Crowell has inside him an abundant reservoir of heartbreak which he draws on to great advantage at rare but crucial moments.

The songs on "Neighbors" aren't generally as strong as those on its excellent predecessor, "I Ain't Living Long Like This." Obviously, "Neighbors" was designed to break Rodney out from a countrified image to a more pop-oriented stardom. The arrangements are less cluttered with steel guitar and fiddle.

Still, Crowell cuts loose on a few down-home songs written by some of his compatriots. And he has penned at least two genuine gems that he delivers with simplicity and urgency. One is "On a Real Good Night," a singer-with-piano tune that strikes just the right b alance between warmth and bitterness. Perhaps best of all is "Ashes By Now," with some of Crowell's favorite images -- booze, heartbreak and packed suitcases. "As much as you burn me baby I would be ashes by now."

That's the line of a writer who's just starting to hit his stride. Graham Nash, with an established following, might sell more records than Crowell this time around. But the '80s will see plenty of hits from Rodney Crowell. t