[General] Rules for non-hero versions of hero abilities

[Yevhen Snizhko]

I want to copy some abilities:

• non-hero abilities - copies will be hero abilities
• hero abilities - copies will be non-hero abilities

I thought that with such abilities, the non-hero version is equivalent to the level 1 version of a hero version, but I see that some abilities were balanced separately across the years.
I can research this more, but I have some questions in case someone already has answers to them.

Questions:

1. What are general rules for abilities that have hero and non-hero version in core WC3 (both RoC and TFT)?
2. If non-hero versions are not always same as level 1 hero versions, what are general ranges of differences?
3. How do these rules apply for ultimate abilities?