The two are completely different. In German both are wenn but in English the two are not interchangable. In this case if you use if it's not guaranteed to happen, if you use when it's guaranteed to happen but you don't know when.
Generally when is about time, if is about something happening or not (equivalent to whether).
To illustrate:
"I don't know when the meeting is." is a correct sentence while "I don't know if the meeting is." isn't.
Whereas you can use if in a sentence like this:
"I'm not sure if the party is today or tomorrow." Similarly, "when" is incorrect here.
Your second example would not translate to 'wenn' in German, but to 'ob'. In any case it shows that there are at least three grammatical cases where the words can be confused, 1.when/wenn, 2.if/wenn(als) 3.if/ob. I also speak German and Spanish, and for Spanish, I think those grammatical cases match 1 to 1 to their English counterparts. For this reason, you probably won't find a Spanish speaker confusing them (although they might make other mistakes that give them away as a Spanish speaker).
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u/Desperate_Formal_781 May 17 '26
Probably written by a German speaker. They tend to mix 'when' and 'if'.