I'm not really seeing any similarities other than both languages having type inference (which is a pretty standard feature of newer languages and as mentioned,

I'm not really seeing any similarities other than both languages having type inference (which is a pretty standard feature of newer languages and as mentioned, Julia was earlier). Julia is competing with Matlab/R/Numpy. That's not what Crystal is targeting at all. I suppose you could imagine that libraries could be written for Crystal, but except for Python's Numpy, these tend not to go anywhere in practice (Ruby itself has the now mostly dead Sciruby for example).