Did the Mirage adaptations seem more like remakes of their 4Kids counterparts?
 

So while you could argue neither really captured Mirage, both have a couple of clear parallels. In particular, the following episodes are heavily based on the same issues:

• "The Shredder Strikes, Part 2" and "The Gauntlet" are both based on Issue 1's conclusion.
• "Meet Casey Jones" and "The Good, the Bad, and Casey Jones" are based on the Raphael Micro.
• "Time Travails" and "Turtles in Time" are both based on Issue 8.
• "Tale of Master Yoshi" and "Tale of the Yokai" both retell the love triangle backstory.
• "Turtles in Space, Part 4: The Arena" and "The Arena of Carnage" are both based on Issue 6
• "Return to New York, Part 3" and "Owari" are both based on Issue 21.

I noticed that these episodes had a couple of similarities not featured in the original stories. At first I thought it was because they're both kids' cartoons and therefore take similar liberties. Makes sense, right? Can't show Shredder die in an explosion after the first battle.

But when I watched "The Arena of Carnage" I noticed it was very similar to "Turtles in Space, Part 4: The Arena", like absurdly similar. They end up in prison, befriend a fellow Gladiator who shares food with them, they fight the spasmosaur, then fight the Gladiator and they all escape in different directions. None of these plotpoints are in the original comic by the way. In fact, if your read the issue then watch the episodes back to back, you'll notice that Nickelodeon omits more from the comic than 4Kids. The only difference is that they arbitrarily changed the names and gave the Spasmosaur eyes.

And I also noticed it copied the 1990 movie to some extent. Which really makes me wonder, did the writers mostly just take notes when watching the movie and 4Kids, more than they read the comics?

Both shows loosely based the episode arcs on the comics and did their own thing with them to match the tone of the show.

Time Travails had a love triangle?

Crap, I meant Tale of Master Yoshi.