The Senate Judiciary Committee heard sharply divergent portrayals of Judge Robert H. Bork yesterday by legal experts who depicted him as both an extremist who could produce "chaos" in the Supreme Court and as an open-minded judicial moderate with a consistent record of fairness.

Laurence Tribe, a well-known liberal professor of constitutional law at Harvard Law School, told the committee that President Reagan's nomination of Bork to succeed retired justice Lewis F. Powell Jr. "seriously threatens the constitutional values that have proven fundamental in our history."

Noting the number of major Supreme Court decisions that Bork has harshly criticized, Tribe added, "Unless he has unusual respect for precedent, putting him on the court may spell chaos."

Bork's supporters countered later in the day with a panel of law professors who described the nominee's views as "squarely in the mainstream."

Carla A. Hills, an assistant attorney general and secretary of housing and urban development in the Ford administration, said Bork's views on the equal-protection clause of the 14th Amendment would result in an expansion of women's rights and pose no threat to women, despite what critics have charged.

Hills said she is confident that Bork would not vote to overturn Roe v. Wade, the Supreme Court's landmark 1973 abortion ruling he has called "unconstitutional." Pressed by committee Democrats on this point, Hills acknowledged that she could not predict Bork's votes on the court.

The conflicting testimony yesterday established what is likely to be the pattern for the Judiciary Committee between now and Oct. 1, the date it has tentatively set for a vote on Bork's confirmation. The committee announced the names of more than 70 witnesses it plans to hear amid grumbling by senators about the pace of the hearings, which lasted 13 hours Monday and almost nine hours yesterday.

Much of the conflict yesterday centered on Bork's views on applying constitutional guarantees of equal protection under the law. Tribe argued that Bork rejects "an evolving concept of liberty," accepting only rights explicitly stated in the Constitution, a position Tribe said puts Bork at odds with all past and present Supreme Court justices.

"It seems to me that in an age of biomedical and technological revolution, that frozen concept of liberty is dangerous," Tribe said.

Asked about Bork's assertion in testimony last week that he might still find in the Constitution rights, such as privacy, that he has rejected in the past, Tribe said: "I don't think constitutional law is a game of hide and seek. The idea there is a right hidden in there that Judge Bork would find is not very plausible."

He dismissed as "mushy" and "an invitation to fill in the blank" the equal-protection standard that Bork told the committee he would use to decide sex-discrimination cases. Until his testimony, Bork had argued that equal-protection guarantees do not apply to such cases.

"I don't think we can afford to say, 'Oh well, it's just one seat {on the court},' " Tribe said. "It's a lifetime seat dealing with lifetime problems. The real question is what risks are we willing to take."

But Hills said most of the advances women have made have come from the enactment of laws, not court decisions, and that Bork's approach of allowing "fine distinctions on reasonable grounds between the sexes" would protect this progress.

"By allowing democratically elected bodies to make these distinctions, Judge Bork is not being less serious about women's rights, as his opponents charge; he is being more sensitive," she said. "In letting legislatures, which are directly responsive to female voters, take into account special needs of women, Judge Bork aligns himself with leading feminist legal theorists."

Gary Born, a Washington lawyer and visiting law professor at the University of Arizona, said Bork has "a consistent record."

"He takes equal-protection guarantees for all people -- blacks, whites, men, women -- very seriously," Born said.

Responding to charges that as a judge Bork has been pro-business and anti-labor, Thomas Campbell, professor of law at Stanford University, described Bork's record in this area as "blah," saying that he has come down evenly in several "rather dull cases."

Michael McConnell, a law professor at the University of Chicago, said Bork's decisions dealing with First Amendment rights were "as strong if not stronger than the current Supreme Court doctrine."

But writer William Styron, author of "The Confessions of Nat Turner" and "Sophie's Choice," said Bork's past statements suggest that "he would not be friendly to writers" and other creative artists.

"It deeply bothers and troubles most American writers," he said.