John Mueller of Google said on Twitter that the GoogleBot user agents do not change based on the type of content they are crawling on the web, specifically, they don't have user agents that are better at crawling JavaScript and AJAX content versus normal basic HTML.
Here are the set of tweets:
@ramirez_robert @methode No special UAs, but rendering isn't always immediate on crawl, maybe that's what you're seeing?
— John Mueller (@JohnMu) August 4, 2016
John Mueller did add that sometimes GoogleBot will not render the full JavaScript on the first pass or first try, it may come back later or render it later. John said, "rendering isn't always immediate on crawl."
Interesting little tidbit of knowledge for some of you laser focused SEOs.
Forum discussion at Twitter.