Terminology for pairs of words with the same meaning, similar or same pronunciation but different spelling

Is there a term describe word pairs like colour/color that have the same meaning, similar or same pronunciation but a different spelling?

The most common examples I can think of are English/American spelling variants, though there are alternative transliterations of foreign words would fit the bill too (e.g., Ziggurat/Ziqqurat).

I was wondering if there is a recognised word for describing these word pairings as we have terminology like "homonym", "heteronym" etc. for words with different meanings.

Solution 1:

The word you could be looking for is variant

Definition:

1 obsolete : variable

2 : manifesting variety, deviation, or disagreement

3 : varying usually slightly from the standard form

(examples) variant readings; variant spellings

Also, from google search:

Solution 2:

This diagram on Wikipedia suggests that there is no such word: