Isekai Quartet

Parody and crossover from several anime with similar themes.  

Various anime series together to form a parody that puts their protagonists in random non-sense scenarios allowing them to interact with each other and deliver some fan-service. If you like some of the anime parodied in there, you could give it a try for a laugh or two but don't go expecting groundbreaking comedies. 

Both shows are crossovers of 4 shows containing similar attributes to them (all isekai's in IQ and all Type Moon works in CP) and both contain lots of parodies about their base shows. They both also require knowledge about the original shows, in order to get the most enjoyment out of them 

Both are parody shows of a particular franchise/genre. Each have a few characters from many shows meshed together in one. 

Both are funny chibi parodies of their original shows, and both have a very lighthearted tone in contrast to their original shows (with the exception of Konosuba) 

Same type of comedy where they parody serious anime by ridiculing the characters in a funny way and with a chibi art style 

Both anime share a chibi art style and are spin-offs Both genres are comedy and are in a school setting 

Isekai Quartet is a parody to the 3 other shows included, putting characters in silly situations they would never encounter in canon. But since Konosuba is already a parody by itself the tone is completely unchanged. If you like the easygoing feel of IQ you're going to enjoy Konosuba. 

Isekai Quartet is an isekai with Chibi characters in which characters from other isekai join a school and among its characters there are also characters from KonoSuba. 

CB Chara Go Nagai World and Isekai Quartet are crossover comedy anime with a chibi art-style in wich characters from different anime are transported into a new world and attempt to figure out what this new world is and how to escape it. They are similar in many ways but what I think are the biggest differences is CB Chara having a more serious plot but still being very comedic while Isekai Quartet chooses to focus on it's characters and their interactions without being heavily driven by a plot. Something that I find interesting is seeing how the characters change and act in ways that you wouldn't see in their original anime. For example, the demon Jinmen goes from being a sadistic, terrifying monster to being a comedy-relief character. And Albedo not looking down on her human class mates as much as she did in Overlord. I rather enjoyed seeing the relationships being formed between the characters such as Akira quickly becoming friends with Koji due to their similar personality and Kazuma declaring rivalry with Subaru due to being in similar circumstances, but with different quality of life-styles If you like the idea of different anime clashing with eachother and wondered how your favorite character would interact with characters from different shows and react when put together in different situations, then you will definetly enjoy this read more 

Both shows are chibi crossovers of 4 related animes.