phrases - What does one's status being “less a blank check than an equation with multiple variables” mean?

There is the following line in a December 8 New York Times article titled “Clinton’s countless choices hinge on one: 2016”:

“But being Hillary Clinton is never a simple matter, and her next few years are less a blank check than an equation with multiple variables. Her status is singular but complicated.”

Though it seems to me the author is simply saying Hillary Clinton’s plans and stand for next few years is unpredictable, I’m not clear with the phrase, “less blank check than an equation with multiple variables.”

Cambridge Online Dictionary defines less than ... as an idiom to describes “behavior which does not have a stated characteristic that is good or attractive.” Readers English Japanese Dictionary defines “less than ...” as an idiom meaning “never be ....”

I know what a blank check is. In the phrase “less a blank check than an equation with multiple variables,” is a blank check more unpredictable (difficult to fathom) than a complex equation, or is a blank check as unpredictable as a complex equation, or is a blank check more predictable than a complex equation (which seems unlikely from the context)?

Can I say “The recovery of Japan’s economy in the past decades was less a snail than a tortoise” in the same construction with “Her next years are less a blank check than an equation with multiple variables?

Answer

In this case, "less A than B" (where A is "a blank check" and B is "an equation with multiple variables"), means that there's two ways you could describe something, but that the first way isn't as accurate as the second.

You can also say "not so much A as B".

http://q.hatena.ne.jp/1124350498 (I didn't deliberately choose a Japanese language website - google is under the delusion that I can read Japanese!) has an example of this with "He is not so much smart as clever." - in that case, you could be tempted to describe that person as smart, but clever would be a more accurate description.