The resurgent Boston Celtics, one of four unbeaten teams in the National Basketball Association, have little in common with the Celtics of the past four years.

The Celtics, young and aggressive, provide a marked contrast to the Washington Bullets, whom they face Friday night at Boston Garden (WDCA-TV-20, 7:30).

The Bullets are injured and struggling and have not played well, except in spurts. They moped around for three quarters against the Atlanta Hawks at Capital Centre Wednesday before coming up with a big fourth quarter and escaping as 100-97 victors, their first success of the season in three ties.

Again, it was Roger Phegley who shone brightest for the Bullets. He scored 19 points, 11 of them in the fourth quarter, including seven straight as the Bullets came back from a 95-89 deficit to a 96-95 lead. They never trailed after that.

Phegley, who is none for two shooting as a guard, has made 20 of 36 shots as a forward and scored 54 points in the last two games.

He will probably also see most of his action at forward against the Celtics because Bob Dandridge is still bothered by strained ligaments in his left foot and he didn't make the trip.

The Celtics have beaten Cleveland twice and Houston, so their contest with the Bullets will be their first against an established playoff contender. w $"We should find out where we really stand after this game," Celtic Coach Bill Fitch said. "The Bullets are a good team and they know what they want to do out there."

The bullets' biggest problem has been atrocious ball-handling. They turned the ball over 54 times the last two games, looking bewildered whenever the opposition threw a press at them.

Guard Kevin Porter, the man who was supposed to make it difficult for any team to press the Bullets, has been slowed considerably by a swollen ankle and has been struggling. He commited 10 turnovers in the last games and played only 22 minutes against the Hawks because of his effectiveness. Porter is averaging 7.7 assists but has made only seven of 23 shots.

The man causing the most excitement in Boston is 6-foot-9 rookie Larry Bird. He and free agent M. L. Carr have teamed with veterans Nate Archibald, Dave Cowans, Cedric Maxwell and Chris Ford to give the Celtics a team that is both fun to watch and successful.

Fitch goes to his bench often and, as a result, has seven players averaging in double figures after three games.

Bird leads the way with a 19.3 average, followed by Carr's 18.3. Cowens, no longer burdened with coaching duties, is averaging 17.3 points and 10 rebounds a game.

Fitch starts Bird as a small forward and uses Carr as his sixth man. Carr, who led the NBA in steals and was second in the league in minutes played while with Detroit last season, said that being sixth man suits him fine.

"I think I can contribute more to this team by not starting," he said. "I'll do whatever coach wants me to and I'll be happy doing it. That's the way everyone on this team feels."

The Bullets return to Capital Centre Saturday to face the Detroit Pistons in an 8:05 game and then will be off until Wednesday, when they face the Pistons again in Detroit.