Jailhouse Rock

Even as the post office weighs whether a new memorial stamp should enshrine the young, teen-idol Elvis or the older, lounge-lizard Elvis, these disc releases prove there wasn't always a lot of difference between the two. Sure, the King looks sleeker and a bit more spirited hamming his way through Jailhouse Rock's ex-con-turns- sullen-pop-star story line. But the twittery James Dean imitation he affects between blasts of great Leiber-Stoller rock (''Baby, I Don't Care,'' ''Treat Me Nice'') seems just as much a put-on as his high-collared nightclub-vulgarian act in That's the Way It Is, an amazingly unflattering documentary-cum-concert movie directed by Denis Sanders. Fortunately, the laser format lets you treat both films like CDs, using the chapter-skip button to savor the best songs without wading through Jailhouse's awful dialogue (''Your larynx looks as good as it ever did,'' a doctor chirps) and That's the Way's interminable visits with obsessed fans. Like so many Elvis flicks, these two are practically camp, but the insolent star at their center is never less than riveting. C+