Not quite. The green dots with are an indicator of the popularity of search terms within each question branch at the time the report was run.
To be clear popularity does not always = highest search volume. Low volume but new trending relevant terms can appear higher than high volume terms.
i.e. Both Common and Trending keywords are part of autocomplete data. Which is what we use to generate our reports.
Darker Green = More Popular.
Some more detail...
Autocomplete aims to predict which are the most relevant searchers to the keyword you are typing. The predictions are made up of common (likely to be higher volume on average) and trending suggestions (perhaps new search terms with less volume, but they are trending) relevant to the characters that are entered.
If the results were only ordered based on high search volumes, things like brand new products/models/events relating to a keyword would not appear. i.e., the search volume would be too low vs. other generic terms. So by including trending (popular) keywords, more timely and relevant results can also be shown.
You can read more about how auto-complete works here:
https://www.blog.google/products/search/how-google-autocomplete-works-search/