[quote=@Double Capybara]
Recently I started to use an app to improve my vocabulary. It is a bit odd. Like:

Elusive 
You picked "vague"
Correct answer: hard to pin down.

Am I mad? Isn't this all synonymous?
[/quote]

Nope! You're fine, they just messed up their description. Vague is fuzzy or faint, without having clear details or limits. Elusive is specific, but hard to catch- Say, a solution to a problem definitely exists, but nobody's figured out what exactly it is yet.