Motown's 25th anniversary has spawned a set of four reissues that, if nothing else, make it clear there are really two Motowns. They began with Detroit assembly-line worker Berry Gordy Jr., who created the most successful black business and record company in the United States.

The first Motown is the little, family-like company that proclaimed itself "Hitsville, USA" and proved it between 1963 and 1966 by releasing an incredible number of pop classics.

Smokey Robinson's productions of Mary Wells, the Temptations and the Miracles, and the Holland-Dozier-Holland productions of the Vandellas, the Supremes, and the Four Tops remain some of the most brilliantly conceived, impeccably realized and irresistible singles ever released. This is the stuff the fraternities, the preppies--all of us, for that matter--will move to forever.

After 1966, however, the success of the Memphis soul sound and Sly Stone's adventurous pop fusion moved Motown off the cutting edge of black pop. Motown slowly devolved into just a great and successful record company. They still had tons of talent in producers Norman Whitfield, Nicholas Ashford and Valerie Simpson and in artists like Marvin Gaye, Stevie Wonder and the Jackson Five. But by the late '60s, they were chasing trends in black music as often as they were creating great musical moments.

The move to Los Angeles in 1971 and the company's huge investment in Diana Ross' quest for superstardom were the final steps in demythologizing this great hit-making machine.

"25 No. 1 Hits From 25 Years" (Motown 5308 ML2) is a double-album set that unfortunately is exactly what it claims to be. Although there's nothing really wrong with any of these smashes, by choosing only number one hits and spanning two decades of dynamic change in black pop, the album ends up lacking artistic focus or even nostalgic impact. It is certainly not a history of Motown at its best.

Only six of the 25 hits are from the pre-1967 period, meaning Motown has yet to provide a comprehensive collection of material from its classic period. The five-album set, "The Motown Story," released in 1970, could have served that purpose if not for the spoken remembrances that marred the beginning of each and every cut. Here, the restriction to number-one hits means, for example, that Martha and the Vandellas are excluded, as well as all of the Miracles' mid-period classics like "Tracks of My Tears."

If nothing else, however, it marks the spiritual decline in Motown's music (and perhaps in the pop industry as a whole) as the needle moves from hit No. 1, the brash dance-floor insistence of the Marvelettes' "Please, Mr. Postman" in 1961, to hit No. 25, the limpid lounge-chair romanticism of Diana Ross' and Lionel Richie's "Endless Love" in 1981.

An even less musically elegant and inspiring collection of Motown successes is "25 Years of Grammy Greats" (Motown 5309 ML), a set of 10 Grammy nominees and winners. While seven of the 10 songs are from the '70s, the album does stretch from Martha and the Vandellas' "Heat Wave" in 1963 to the Dazz Band's "Let It Whip" in 1982. Again, the problem is simple. A successful compilation needs an artist, theme or style to provide the fan with a coherent listening experience and the often bizarre, industry-contrived selections represented by the Grammys just won't do.

Excluding the highly personalized art of Stevie Wonder and Marvin Gaye, two new double-album collections of hits, "Diana Ross Anthology" (Motown 6049 ML2) and "Commodores Anthology" (Motown 6044 ML2), provide a clear view of the nature of Motown's pop triumphs in the '70s.

Teamed with a variety of producers and songwriters, Ross' liquid voice and sophisticated allure resulted in five number-one hits during this decade. Side 1 is the best here, featuring the classy soft ballads and tastefully arranged productions like "Reach Out and Touch" and "Surrender" that Ashford and Simpson provided.

Before the decade was over, a range of forgettable supper-club Ross hits would be produced by Richard Perry, Stevie Wonder, Bernard Edwards and Nile Rodgers--all proof that Ross has always been a pliant piece of pop fantasy material waiting for the proper collaborators.

In most respects the Commodores collection is much more interesting simply because this band moved through the full funk-to-soul-to-pop domain that defined black music in the '70s. Again, the earliest hits sound best here, moving from the Commodores' first big smash, the tough synthesizer instrumental "Machine Gun," to funky dance material like "Brick House" and "Slippery When Wet."

There's no doubt this six-piece band was loaded with talent, but it was the ascendance of Lionel Richie as a warm balladeer and sentimental songwriter that brought the group its biggest hits like "Three Times a Lady." While they still balance dance with romance, this maturely professional group has now settled into the slow-moving, but eternal stream of bland pop that symbolizes the current wave at Motown.