It is rare and amazing occurrence when an NBA team or player is on the verge of making history, becoming the first to reach a milestone and thus setting a league record.

It is even more unlikely and special to see two parties on pace to beat the same record at the same time.

That's exactly what is happening this season with the Toronto Raptors and the Golden State Warriors and their historic offensive ratings.

A team's offensive rating is a measure of points scored per 100 possessions. Adjusting for how teams play with a variable pace during a standard 48-minute game, offensive rating is a widely accepted metric that can be used to compare teams and their offensive efficiency, based on how many points they score on a per-possession basis.

The current league record for offensive rating was set by the 1986-87 Los Angeles Lakers (a.k.a. Magic Johnson's "Showtime" Lakers), one of the NBA's historical gold standards (pun intended) for offensive proficiency. Their 115.6 offensive rating has only been threatened a couple times in the last 10 years, namely by a few of Michael Jordan's Chicago Bulls squads, Larry Bird's Boston Celtics, and the "seven-seconds-or-less" Phoenix Suns.

Almost a third of the way through the 2016-17 season, however, both the Toronto Raptors and Golden State Warriors are on pace to set a new record for offensive efficiency with rates of 117.6 and 116.3, respectively.

Here is how the top-10 offensive ratings of all time would stand if the season were to end today.

The most interesting thing about the fact that these two teams are neck and neck to have the two most efficient offenses in the history of the Association is that they are doing it in completely different ways.

Let's take a look.

Efficient Shooting, Ball Protection, and the Slow Grind

The Toronto Raptors are not what we would consider a modern NBA offense. In the "pace and space" era of the league, where easy transition baskets and three-point makes are coveted by the bucketload, the Raps don't do a lot of either. They are 23rd in the NBA in pace with 94.8 possessions per 48 minutes, rank 18th in transition possessions per game with 14.7, and 23rd in three-points attempts per contest at 24.5.

But what they lack in volume in those areas, they more than make up for with efficiency.

While they are in the bottom half of the league in transition possessions per contest, they are number one with a bullet when it comes to points per transition possession at 1.31. And although they don't shoot a ton of threes per game, they make a higher percentage of them than just about anyone in the league. As of today, they are tied with the Cleveland Cavaliers for first in the Association in three-point percentage at 39.9%.

Speaking of shooting percentages, the Raptors are pretty well solid across the board. They currently rank second in the NBA in field goal percentage (47.6%) and second in free throw percentage (82.1%). They are the only team in the NBA to rank in the top-two in all three standard shooting percentages, while coming in fourth in effective field goal percentage (weighted twos and threes) at 53.3% and third in true shooting percentage (weighted twos, threes, and freebies) at 58.1%.

Their hex map (advanced shot chart) is glorious, with there being only one section of the court (the mid-range on the left side or the blue area below) where the Raps shoot below league average:

Finally, Toronto's efficiency on the offensive end largely has to do with their ability to protect the ball and not waste possessions. Although sometimes criticized for being 29th in the NBA in both assist percentage (50.6%) and passes per game (271.6), they are also first in turnover percentage at 11.0%.

While we have come to value ball movement and always looking for the best shot in basketball, there is something to be said for the way that the Raptors limit turnover opportunities and make their possessions count in other ways.

Pace, Space, and Three-Pointers in Your Face

If the Raptors are the antithesis of modern "pace and space" basketball, the Warriors are the epitome of it.

They are third in the NBA in pace at 100.1 possessions per 48 minutes and shoot the fourth-most threes per game at 31.6. They also lead the league in transisition possessions per game with 18.7, while coming in fourth in points per transition possession at 1.18.

Another part of the reason that the Warriors are historically efficient on offense -- and yet another way that they're doing it in a polar opposite way from the Raptors -- is that they are making another play at NBA history this season: their 31.4 assists per game matches the league record set by the Los Angeles Lakers during the 1984-85 campaign (reminder: the 80's Lakers teams were fun).

But one way in which the historically efficient offenses of the Warriors and Raptors are very similar is in their dominant shooting percentages. The Warriors rank sixth in three-point percentage (37.7%) and come in eighth in free throw percentage (78.5%), while leading the league in all three of field goal percentage (49.4%), effective field goal percentage (56.2%), and true shooting percentage (59.8%).

Their hex map is just as stunning as the Raptors', with above the key being the only area that they are shooting below league average (the blue spots below):

To Each His Own

The Toronto Raptors and the Golden State Warriors are both vying to be crowned the most efficient offense in NBA history. The Raptors are slowly grinding out possessions, limiting turnovers, and shooting the lights out, while the Warriors are getting out and running, bombing away from long range, and...well, also shooting the lights out.

There are many ways to skin a cat, as they say, and the dichotomy that exists between these two historically great -- yet entirely different -- offenses is a perfect example of that.

No matter which style of basketball you prefer, it will be exciting to see if either of these teams can beat the record over the course of a full season and which one will ultimately come out on top.