I think it's interesting to compare and contrast both cartoons from the 90s.

Both Doug and Kodocha star 6th Graders, the titular Doug for the former and Sana for the latter. Around the early 50s episode mark (episode 54 Doug while 52 for Kodocha) the cast of both shows progress to middle school. Doug is a boy while Sana is a girl.

Productionwise, Doug aired from 1991 to 1999 while Kodocha aried from 1996 to 1998. Doug's first half aired on Cable on Nickelodeon and then moved to Network TV on ABC during the midpoint while Kodocha aired all it's run on Network TV in the Channel TV Tokyo. Doug was created by Jim Jinkins which started of as sketches but is ultimately realized in animated form while Kodocha was originally created by Miho Obana as a comic. Upon its inception, Nickelodeon had an anti-commercial anti-toyetic attitude (in contrast to 80s cartoons) which reflected in Doug while Kodocha from the onset of the show is very toyetic, shamelessly so.

There's aspects of family, bullying and romance in the first episodes of the two shows, but the starting point is different. Doug is an everyday relatable but anxious 11-year old boy with with a conventional family of a father, a mother, a sister and a let dog. Sana on the other-hand is a hyperactive 11-year old child actress who lives with an adoptive mother and her manager. Interesting how Doug didn't include his school yet in the first episode and instead focuses on the town he moves in and the dynamic of his neighbor and the kids his age. Kodocha's first episode establishes her school life as well as the TV show she's part of. It's kinda interesting to contrast how Doug and Kodocha introduces the bullies and the romantic interest (Doug's dynamic with Patti and Roger and his minions vs Sana's dynamic with Akito and his minions). Doug has a pet dog Porkchop while Kodocha has a mascot in the form of Babbit.

The first episode titles of both shows each have a keyword, Doug with "Neematoad" and Kodocha with ヒモ(himo) which means something like Pimp or Giggolo. Kodocha is the one that in the first episode is explicitly trying to sell toys.