This CD cover image released by Warner Bros. Records shows "Kiss Me Once," by Kylie Minogue. (AP/Warner Bros./AP)

Kylie Minogue’s new album, “Kiss Me Once,” is being called a comeback, which isn’t technically true — her last few releases have been solid hits. But Minogue is a 45-year-old pop diva, making her practically a senior citizen in club years, so she’s got to fight her way back every time.

While Minogue must remain eternally youthful, George Michael, 50, might as well be 70. After his success in the ’80s with Wham!, a still-in-his-20s Michael settled into an occasionally musty adult-contemporary groove and has refused to budge. He rarely releases albums; has been arrested on an array of drug, lewd conduct and driving offenses; and is seemingly regarded with distant fondness by his fellow Brits as the charmingly addled, pot-smoking uncle they only see on holidays.

This week, Michael releases the pretty-much-live album “Symphonica,” which solidifies his reputation as a somber, elder-beyond-his-years statesman. Minogue tried seriousness once, but it didn’t take; it’s not her fault we only want a few things from her, most of which she delivers on this gossamer-winged new album.

The tinny Europop of its predecessor, 2010’s “Aphrodite,” suggested Minogue worried about Lady Gaga, who was then coming up hard in her rearview mirror. “Kiss Me Once” owes an equal debt to Daft Punk, but otherwise follows the formula Minogue and countless other pop divas of any age have been following for years: Enlist of-the-moment songwriters and crossover DJs/producers to apply a fresh coat of lacquer to your malleable, bedrock sound — in Minogue’s case that means shimmery, content-free disco pop with a retro feel.

The funky “I Was Gonna Cancel” was written and produced by Pharrell Williams; it’s a factory-issue jam, but it’s the best thing here. The lyrics (“My best friend is the mirror /Look behind me and I see all the things I’ve been through / . . . Go go go go girl”) are almost a parody of what Pharrell thinks women think, but at least he’s trying. And if, after three decades of cheerily impersonal pop, no one has the slightest inkling what Minogue really thinks about, dreams about or wants, it’s nobody’s fault but hers.

Sia Furler was presumably brought on board because of her ability to articulate on these topics, but her journey from intelligent singer-songwriter to lowest-common-denominator-enabler of pop princesses (she wrote Britney Spears’s recent, not-creepy-just-sad non-hit “Perfume”) has become increasingly depressing to witness. Furler wrote the bouncy, unrelenting “Sexercize,” which is as bad as its title suggests, maybe even worse. “Sexercize” doesn’t make a case for itself as either an activity or a song. (“Stretch it out, baby . . . I want to see you beat all your best times,” Minogue encourages.)

Song selection also plagues Michael’s “Symphonica,” which is an unaccountably strange creature — a not-entirely-live collection of covers and little-known originals, many of them drawn from his 1999 release, “Songs From the Last Century.” The last album produced by the legendary Phil Ramone before his death last year, “Symphonica” appears to have undergone more than the standard amount of studio sweetening, with Michael’s 2012 orchestral tour serving as a foundation.

Michael has made a career out of thwarting expectations, abandoning almost every conventional trapping of pop-star careerism and instead issuing defiantly noncommercial albums at a leisurely pace (his last official studio release, the prophetically titled “Patience,” came a decade ago).

Spend 27 years consulting only your wishes, and you too might emerge with something like “Symphonica,” a lush, logy collection of weapons-grade bummers. The songs appear selected for their ability to invoke misery and frustration in equal measure, as if Michael consulted some unseen Index of Undesirability before choosing them.

These tracks tend toward the mournful, which is as it should be. Michael lacks the lightness necessary to make the nominally happy songs (such as “Feeling Good,” once famously covered by Nina Simone) swing, but he makes masterful work of the gloomier ones, such as the Depression-era standard “Brother, Can You Spare a Dime?,” which he doesn’t sing so much as regard sternly.

Michael mines his back catalogue for obscurities, which is different than saying treasures: For every hit (such as a sublime, gospel choir-backed rendering of “One More Try”), there are three or four random ones, such as the stodgy, synth-y “John and Elvis are Dead,” about a disillusioned coma victim.

Artists must first please themselves, but there’s something about the way Michael, after a decade’s absence, disregards pop music’s basic pleasantries that doesn’t feel brave or rebellious but rather perverse and purposeful, as if he were waging some sort of war of fan attrition.

Michael may be a prematurely old, withholding grump, but the studied blitheness of “Kiss Me Once,” on which Minogue labors so hard to appear ageless (women aren’t allowed to seem prematurely old) and hews so carefully to the musical dictates of early 2014 that her personality gets erased, is equally hard to witness. Michael, rumored to be releasing a comeback album this year, may have a complicated relationship with fame, but Minogue is holding on as hard as she can.

Stewart is a freelance writer.