That's the Way It Is is arguably where Elvis Presley's discography gets very confusing.

Sharing a title with Denis Sanders' 1970 documentary of Elvis' return to the stage, That's the Way It Is in its original 1970 LP incarnation isn't precisely a soundtrack to the film.

In fact, only a third of the album captures Presley live on-stage in Vegas, with the remainder of the record derived from sessions he recorded in Nashville just a few months prior to launching his long-standing gig at the International Hotel.

Vegas looms large over Elvis' legend in the '70s and many of the clichés -- the jumpsuits, the splashy arrangements of contemporary standards, the snazzy melodies of his old hits -- were born on That's the Way It Is, either on film or on the record.

In its original LP incarnation, this wasn't especially apparent due to the record's reliance on the Nashville sessions, where Elvis recorded a fair share of perfectly pleasant middle-of-the-road material pitched halfway between Hollywood and Music City.

These tunes -- "Twenty Days and Twenty Nights," "How the Web Was Woven," "Just Pretend," and "Stranger in the Crowd" -- are easy to spot because they're by songwriters without marquee names (Colonel Tom Parker insisted Elvis take a larger percentage of publishing, which kept away many writers) and, more tellingly, on the 2014 expansions of the album -- available in a double-disc set, which presents a remastered version of the original album supplemented by single versions of four tracks ("I've Lost You," "The Next Step Is Love," "You Don't Have to Say You Love Me," "Patch It Up"), five outtakes of alternate tracks, then a full set from August 12; there is also a gigantic eight-CD/two-DVD box that replicates that expanded first disc and six full sets recorded during the filming of the documentary, plus a disc of rehearsals -- these are the songs that don't appear in the live set.

They may not have been part of Presley's repertoire but they do indicate how he was shifting away from the soulful, funky sound inspired by his 1968 comeback into something that felt showbiz.

The live recordings, though, show that he was still performing with passion, figuring out what worked on-stage and what didn't after his long hiatus from performing.

Again, this isn't so apparent on the 1970 LP, which was basically a good studio album that essayed Elvis' new persona for the coming decade, but all the various expanded editions (which include a 2000 special edition that adds a hefty dose of live material) capture the King starting to relax and enjoy his reign yet again.

Certainly, the eight-disc set illustrates this in spades, and while it's undoubtedly one for the devoted, it nevertheless isn't overkill because it captures a peerless performer putting his amazing band through the paces.

It's wonderful music that actually is more valuable now than it was at the time: Elvis would record more great music in the next few years, but this record -- especially in its 2014 expansion -- captures him at a pivotal moment, when he retained the power of his 1968 comeback and had yet to succumb to all the glitz of Vegas.