voceplatforms

Jeff Stieler

Kevin Langley Jr.

Adds meta boxes to all post types and allows you to convert the post type of the current post you are editing to a different post type. This very useful when doing an import from another site into one post type that then needs to be filtered into different post types or even to fill dummy posts throughout multiple post types.
Please refer to full documentation at https://github.com/voceconnect/post-type-converter/wiki.

Post Type Converter

Allows you to convert the post type of objects while in the edit screen.

kristarella

Copy or convert terms between taxonomies.
Taxonomies include categories, tags and any other custom taxonomies that may be present with your active theme and plugins.
This plugin, based on Categories to Tags Converter, allows you to copy (duplicate) or convert (move) terms from one taxonomy to another or to multiple taxonomies, while maintaining associated posts.

Taxonomy Converter

For starters, the plugin has deprecated code and produces errors on PHP7. Looks like the code hasn't really been touched all that much in many, many years.

The biggest problem is that when the terms are converted, the term descriptions are removed.

Doesn't include term descriptions

Copy or convert terms between taxonomies.

Post Type Converter vs Taxonomy Converter