There's no difference between the requirements for ICAO Level 4 in English, Spanish, French, German or any other ICAO recognised ATC Language.
Except that non-English native speakers have to achieve level 4 proficiency. As someone whose brain does not seem to take to learning languages I count myself very lucky - pretty much every day - that I was born into an English-speaking environment. Just imagine, if history had been just a little bit different, we could all have had to learn a completely, to some of us, alien tongue just to do the day job!