It’s software cad. You write code that makes the 3d model. And then you print the 3d model.
The last “official release” was 2 years ago. But development (and community) is active. You gotta get the nightly builds.
Tbf, comparing blender and openscad is more like comparing a hammer with a knife.
FreeCAD would be the more obvious comparison here - and while Openscad has some benefits for more complicated projects it is less than optimal - and sadly FreeCAD still sucks compared to most commercial products,even though it has improved recently due to the ONSEL influence.
I never heard of opencad before today so its interesting to here something new to me. 3 min tutorials makes it Seems like requires some “coding” which seems like a much higher barrier of entry. I’m curious how you would get complex details in it. My models have Ornate details after the base shape. I have all kinds of blender tricks to make it happen.