What are the 2 nfl teams that played each other the least and the most?

As of the end of the 2020 season, all of the current NFC West have played only 4 games against the Houston Texans.

• Seattle Seahawks
• San Francisco 49ers
• Los Angeles Rams
• Arizona Cardinals

That the Texans are involved here is not surprising as they the most recent expansion franchise in the NFL, beginning play in 2002. Unless amended, the rotating schedule of NFL matchups pairs the NFC West with the AFC South in the 2021 season, so the Texans will play all the above teams in the 2021 season.

The record for the most head-to-head matches goes to Chicago Bears vs. Green Bay Packers with a stunning 202 games.

Stats taken from here (HOU), here (CHI)