Differences between "technic" and "technique"

Technique is the standard spelling. Technic is a variant, for example used for trade names such as by Lego and Panasonic and may sometimes be pronounced with a shorter unstressed i.

Technique and technic are synonyms (as shown on Merriam-Webster's entry for technic).

Note that technique is by far more used than technic. Compare the number of matches found for the two words:

Corpus of Contemporary American English (COCA)
technique = 13383
technic = 18

British National Corpus (BNC)
technique = 4601
technic = 9

Google
technique = 271M
technic = 14M

According to the data from Google Ngram Viewer shown below, technic was more commonly used between 1900 and 1970 than it is today. As for technique, usage increased since the early 1900's until now, except in the past two decades or so, in which for some reason (?) the number of occurrences decreased in comparison to other general words.