It's the "r" that's usually the give away. However, I would have to say that the...

chris_wot on Jan 20, 2013 | parent | context | favorite | on: So you think you can tell Arial from Helvetica?

It's the "r" that's usually the give away. However, I would have to say that the capital "S" is also a giveaway, and the I'd have to say that the letters with Helvetica are somewhat fatter...