THE COLLECTIONS ROD STEWART -- "Greatest Hits" (Warner Bros. HS 3373). BEE GEES -- "Bee Gees Greatest" (RSO RS-2-4200).

No matter how you approach them, "greatest hits" packages provoke the inevitable questions of omission and inclusion: why were the artistic triumphs left off and the failures given another lease on life?

Rod Stewart's "Greatest Hits" is a study in omission. Little consideration appears to have been given to Stewart's best, such old favorites as "Twisting the Night Away," "If Loving You Is Wrong," "Reason To Believe," "Losing You" and a host of others.

Instead, stewart's "Greatest Hits" is a scattershot retrospective on the career of a bluesy rock'n'roller-turned-campy cock of the walk. Except for "Maggie May," from "Every Picture Tells a Story," all the cuts -- including the drivel of "Hot Legs" and "Da Ya Think I'm Sexy?" -- are from the post-Faces era which marks the decline of Stewart the rocker and the rise of Stewart the androgynous sex symbol.

You'll have to suffer through the likes of "The Killing of Georgie," "Tonight's the Night" and "I Don't Want To Talk About It," none of which should share the same vinyl with "Maggie May."

Fortunately, this is only Volume One of what, we can assume, will turn out to be Warner Brothers' answer to Mercury's two-volume "The Best of Rod Stewart," and the follow-up album, "Sing It Again, Rod." We can only hope that Volume Two will offer as much pleasure as Volume One brings embarrassment.

Warner Brothers should take lessons in packaging and marketing from impresario Robert Stigwood and his boys wonder, the Bee Gees. Ever since the pudgy Australian formed RSO Records in 1973, he's orchestrated the careers of the Brothers Gibb with one eye toward bettering their image and the other toward fattening the return on his investment.

His efforts in this area peaked when the sales of "Saturday Night Fever" reached 35 million units and hit bottom with the critical and financial pummeling sustained by "Sergeant Pepper's Lonely Hearts Club Band." Then, earlier this year, Stigwood and the Bee Gees got back on the tracks with the "Spirits Having Flown" album (now into five million units).

"Bee Gees Greatest," a two-record set, is the inevitable next step. For the most part, it's a well-executed step indeed.

All 20 cuts were selected to represent the best of the band's RSO period. Many earlier hits, such as "How Can You Mend a Broken Heart?" "Massachusetts" and "Lonely Days" were covered on the "Bee Gees Gold" albums from Atco.

"Greatest" stars with "Jive Talkin'" from "Main Course," the band's 1975 comeback album, and stretches four years to include "Tragedy" and "Too Much Heaven" from "Spirits Having Flown."

In between are four singles from "Saturday Night Fever," a couple of hits from "Children of the World," an undistinguished and previously unreleased cut and "Rest Your Love on Me," the sappy B-side of "Too Much Heaven."

Strictly in terms of omission and inclusion, Stigwood and the Bee Gees have come as close to a happy medium as could be expected.

One would be hard pressed to come up with any glaring ommissions, and certainly no one could accuse Stigwood of padding the album with fluff -- that is, assuming you don't consider the Bee Gees the personification of fluff to begin with.

It's testimony to Stigwood's obsession with the singles format that all 20 cuts fit so nicely, five cuts to a side, on two albums. "Tragedy," at just over five minutes, is one of the longest songs the Bee Gees hav ever recorded, and seems to have staked out the limits of the band's ability to sustain interest. Few of the other cuts venture far into the fourth minute.

In short, the Bee Gees are a singles band (having just this year taken the No. 1 singles, cahmpionship from the Beatles with seven No. 1 singles in a row), and as such, unlike Rod Stewart, are best represented by collections like "Greatest."

Within the narrow confines of their subject matter (love blissful, love lost, love regained), the Bee Gees are uncontested champions. Let's hope for Stigwood's sake they never aspire to anything more profound.