Korean and Spanish, the same? For me, Korean is more difficult than Japanese, though Japanese's writing system will take longer to learn because of the extensive and somewhat odd use of kanji (Chinese characters). But Japanese grammar is generally simpler than Korean's, and sounds are much easier to distinguish.

I'm nearly fluent in Korean after years of effort. My Japanese far is weaker, but with far less effort put in. I'm nearly native level in French so biased, but I find Spanish to be almost effortless to learn compared to Korean or Japanese (which are actually closely related). Just, like, memorize a bit, get some simple grammatical rules down, and if you don't remember you can test out the latinate word from English. It's cognate heaven. Korean and Japanese are like from another planet, once you get past the initial hotel-and-taxi stuff.

Reading Korean is surprisingly easy: http://www.ryanestrada.com/learntoreadkoreanin15minutes/

I'm guessing that for Korean it's mostly the grammar differences, honorifics, and writing system.