Here are strengths and weaknesses of the Bullets and Boston Celtics, who today in Boston open their NBA Eastern Conference best-of-seven semifinal series. The Celtics won the season series, 6-0; two of the victories were by one point each.

SHOOTING

Boston: The Celtics are versatile. They have runners and gunners in M.L. Carr (8.1), Cedric Maxwell (14.8) and Gerald Henderson (10.2); inside scoring from Robert Parish (19.9) and Kevin McHale (13.6); scoring from everywhere from Larry Bird (22.9). Chris Ford is the best three-point shooter (20 for 63). Carr and playmaker Tiny Archibald are the only players (among the Celtics' first seven) not to have shot better than 50 percent this season. Every member of the team is adept at the fast break, and when they have to set up, the Celtics are still accurate. Maxwell is a clever inside player. Parish has a virtally unstoppable turnaround jumper and a jump hook. Team shooting percentage: .499.

Washington: Greg Ballard is the Bullets' most consistent outside shooter; Kevin Grevey's hitting top form (four of four from three-point territory in the decisive game of the first-round Nets series) gives the Bullets further long-range threat. Spencer Haywood and Frank Johnson also have good jump shots, which the Bullets will need if they are going to play half-court style. Jeff Ruland, a 56 percent shooter, will have his hands full inside against the physical Celtics. Rick Mahorn, whose medium-range jumper was a key factor in the first playoff game against New Jersey, will have to make that shot against Boston, too. Don Collins is the best Bullet in open court, but with Coach Gene Shue not wanting to get into a very fast-paced game, Collins may be reined in somewhat. Team shooting percentage: .474.

Edge to Boston.

REBOUNDING

Boston: The Celtics go to the boards as hard as any team in the league, averaging 15 offensive rebounds a game, third in the NBA. Bird and Parish lead the way with 10.9 and 10.8 rebound averages, respectively. This is an excellent team at defensive rebounding, the key to the Celtics' fast break. Their rebounding depth, with McHale and Rick Robey, is as impressive as their scoring depth. When the Celtics use the 7-foot Parish and 6-11 McHale together, the opposition finds it tough to get a shot off inside; those two average a total of five blocked shots a game.

Washington: Ruland led the Bullets over the season (9.3) and had 20 in the first game of the New Jersey series. Mahorn averaged 8.8 for the season, and equaled that against the Nets; he must do even better against the Celtics. Ballard is a good rebounder for a small forward (8.6), but is going against Bird, pro basketball's top rebounding small forward. Haywood will have to help out a great deal.

Advantage, Boston.

DEFENSE

Boston: The Celtics' defense keys the Celtics' offense. With intimidators inside in Parish and McHale, the guards can double-team and go for steals. Not an array of great individual defensive players, but they play defense as they play offense--as a team. The Celtics don't do much trapping, but will press full court as a surprise tactic.

Washington: If the Bullets are to achieve the upset, it will be with defense. Collins showed with his guarding of the Nets' Ray Williams that he has the skill to be the Bullets' defensive stopper; he may be called on to help guard Bird. The Celtic forward will take him inside, though. Shue and company employ more traps and combinations of presses, traps and intricate defensive sets than any rival in the NBA. Mahorn is the key. He has to orchestrate it all and back up everyone. The Bullets held the opposition to a league-low .465 shooting for the season.

Slight edge to the Bullets.

DEPTH

Boston: The most reserve strength in the NBA. By using Bird, Archibald and Ford as reserves the last quarter of the season, the Celtics prepared Carr, Henderson and McHale for the playoffs and Danny Ainge got much-needed playing time. The Celtics won't be worn down. Robey as relief for Parish means foul touble won't hurt them that much, either.

Washington: Ruland, averaging 15 points and nine rebounds a game, was one of the best sixth men in the league and now, with Grevey back in form, the Bullets have a productive bench. Charles Davis has played well in relieving Ballard. John Lucas, a key substitute much of the year, played only a total of 15 minutes in the Nets series.

Strong advantage to Boston.

GENERAL

The Celtics are the defending champions, own the league's best 1981-82 record and won 26 of their last 30 games. The Bullets are playing as well as they can play, but their only chance is to slow down the action and not let the Celtics get the easy baskets they thrive on. The Bullets are prohibitive underdogs. To win, they not only have to play almost a perfect series but need for Boston to be off its peak. Milwaukee vs. Philadelphia

With Darryl Dawkins back, Philadelphia seemed as strong at playoff opening as at any time all season. Then Lionel Hollins broke the knuckle of the little finger on his left (shooting) hand and fellow 76er guard Andrew Toney sprained an ankle Friday night in the finish of the miniseries sweep of Atlanta. The Bucks have serious injury problems; Quinn Buckner and Junior Bridgeman are out for the duration. Brian Winters is back at guard after missing the last seven regular-season games with a groin pull. The Bucks won the season series, 4-2, but with their guard corps so weakened, they are not the same team. The 76ers will press and it should be a wide-open, fast-paced series. Milwaukee used to be one of the deepest of NBA teams, but the Sixer bench is better now with Bobby Jones and Toney, if he is available. Those two bring a total of 31 points a game off the bench.