A FEDERAL JUDGE HAS just granted a reprieve for Baber Village, the vacant, vandalized low-income apartment complex that Prince George's County wants to demolish and the federal Housing and Urban Development Department wants to save. More than this project is at stake. The basic issue is what should be done, many Baber Villages here and elsewhere - federally subsidized projects, often less than a decade old, that were so poorly designed, hastily built and badly run that they have become financial and social disasters. Prince George's County Executive Winfield Kelly thinks the ruins should be bulldozed. HUD Secretary Patricia R. Harris believes the buildings should be rehabilitated whenever possible to provide more decent housing for the poor.

Some of the talk on both sides has distorted what's at stake. Mr. Kelly has repeatedly made razing Baber Village a keynote of his campaign to bolster neighborhoods and attract more middle-income residents. Thus he is widely seen as inhospitable to lower-in-come families generally. While assailing housing projects, though, Mr. Kelly has been quietly pursuing a responsible strategy of using rent vouchers and subsidies to help poorer residents afford existing housing in many areas. His record is considerably better than his rhetoric suggests.

Nor is the question whether Baber Village should be "revived." We doubt that HUD wants to recreate a disaster any more than local officials or the project's neighbors do. Instead, HUD officials seem to believe the buildings can be not so much revived as transformed into a new kind of complex - one that would be not just safe and clean, but also financially sound, socially stable and acceptable to the community.

That's tall order. Rehabilitating the structures may be faster and less costly than starting from scratch. But shoring-up and remodeling would be just the start. A real salvage program would also require adequate operating and maintenance funds, strong management, sensitive community-relations efforts and new facilities and services for tenants, especially children and the elderly. This has been done occassionally, but involves far more resources and attention than public-housing programs usually provide.

The court has given HUD a little time to show whether it is really prepared to make such a sustained commitment. The agency should draw up detailed plans at once - within the next few weeks. That will let everyone evaluate what the odds on successfully salvaging Baber Village really are. It will also force HUD to spell out the demands and costs of its policy in general. Good intentions aren't enough. HUD has to either put up or let Mr. Kelly tear down.