What is the difference between this project/repo and github.com/OpenAPITools/openapi-generator ?

Description

I have been trying out all the open api generators for Golang that I can find, and I noticed that the client sdk created by this project (swagger-codegen) is basically identical to the client sdk created by OpenAPITools/openapi-generator
There was a slight different in the names of a few functions. And the golang code created by swagger-codegen would not compile because it forgot to generate one of the models it needed. But other than, it was basically identical.

Is one of the projects a fork of the other? Are both under active development?

Swagger-codegen version

3.0.61

Swagger declaration file content or url

https://github.com/veqryn/awesome-go-api/blob/main/openapiv3/openapi_v3.0.3.yaml

Command line used for generation

swagger-codegen-cli generate -i openapi_v3.0.3.yaml -l go -o ./swagger_codegen/go/gen/

Steps to reproduce

Swagger Golang Client: https://github.com/veqryn/awesome-go-api/blob/main/openapiv3/swagger_codegen/go/main.go
(ModelMap was never generated, though it is referenced by the generated ModelError struct)

OpenAPITools Golang Client: https://github.com/veqryn/awesome-go-api/blob/main/openapiv3/openapi_generator/go/client/main.go

Suggest a fix/enhancement

Clarify the difference between the projects.
(and fix the bug)

Start by running the supplied swagger-codegen-cli command against openapi_v3.0.3.yaml and compare its Go output with the linked OpenAPITools output. Inspect the generated main.go files and the referenced ModelError and ModelMap types; done means explaining the project relationship and correcting the missing model generation without breaking the generated client.