Whether you like your Baryshnikov rare or well-done, you'll have your pick of both tonight one television. A serendipitous ballet double-header this evening offers the before-and-after of the celebrated Russian dancer's much-publicized shift from American Ballet Theatre to the New York City Ballet. Back-to-back programs on Channel 9 (30 minutes, starting at 8:30) and Channel 26 (an hour, starting at 9) bring glimpses of Baryshnikov partnering Gelsey Kirkland in his own production of "Don Quixote" for ABT, which premiered in Washington last spring, and Baryshnikov opposite Karin and Aroldingen in George Balanchine's "Prodigal Son," in a complete performance by the NYCB.

The programs could scarely be more dissmilar in aim, atmosphere and achievement. The Channel 9 show, "American Ballet Theatre: Dancing for Love," produced, written and directed by Carol Wonsavage for WDVM, is best at its rarest, that is, in candid shots of Baryshnikov and other dancers in off-stage contexts. The nationally telecast Channel 26 program, directed by Merrill Brockway for the PBS "Dance in America" series, is strongest in its fidelity to the artistic qualities of the dance, and to the chopreorgrapher's vision.

The WDVM show, which is pre-empting the popular net work sitcom, "The Jeffersons," makes an unabashed bid for mass viewership, with syrupy narration and never a strain on the gray matter. The PBS effort, which concedes nothing to the man in the street, is primarily geared to dance enthusiasts and upwardly mobile culturati.

One thing the shows have in common is a goodly amount of television savvy - apropos of dancing. The knowledge, however, is put to very different uses.

The ABT show is a jet-propelled, jump-cut collage that tries to be half a dozen programs in one - a stargazer's potpourri; a smarmy view of the hardships of the dancing career; a backstage peekaboo; a souvenir album of the mounting of the "Don Quixote" production; a capsule history of ABT; and an on-the-spot glitterama featuring President and Mrs. Carter nose to nose with ballet superstars. It's amazing how much detail is packed, quite fluently too, into a half-hour, especially since the show was produced last spring under very trying restrictions from unions and ABT, which needed to rehearse without the obtrusion of camera crews. These conditions account for some of the anomalies (wrong music with dance sequences) and errors (proper name misspellings) along the way.

There are some wonderful shots of Baryshnikov skyrocketing across a studio floor and at a rehearsal grimacing and muttering "mess! everybody . . . mess." But it all whizzes by so fast you're hardly sure you've seen it, and meanwhile the narration overlays everything with travelogue breeziness and bathos.

Except for brief, pertinent intermission commentary by Edward Villella (the excellent script is by Arlene Croce), the PBS show, the thrid in a series on the coreography of Balanchine, is pure performance, all of it superb. Baryshnikov uses his weight and muscularly brilliantly to project the expressionistic stolidity of the Prodigal Son, and the final reconciliation with his father, portrayed with warmth and authority by Shaun O'Brien, is extremely touching.