Än, ännu, även. Do they mean the same? Does it matter which one I use?
This is a question I get very often. Fair enough. There is some confusion, and I am pretty sure that your Swedish friends will also get a tiny bit perplexed if trying to explain this.
When using the comparative form of adjectives, än is the equivalent of the English than:
Vintern är kallare än sommaren.
Min man är bättre än jag på att laga mat.
There is rarely any mistakes related to this. What could be interesting for English speakers, though, is that in Swedish, if there are only things or persons in a closed system, to compare, we tend to use the superlative instead of the comparative form. For example:
Han har två barn, Erik och Lisa. Lisa är äldst.
Also related to the comparative form of the adjective, ännu is used as a modifier to the comparative. The equivalent in English would be even, like in even better. Mistakes often occur, and I often hear även instead of ännu. The correct formulation is:,
Igår var det varmt, men idag är det ännu varmare.
Medicinen gör så att Jonas mår ännu sämre.
Although mistakes are common, the difference between än and ännu, so far, is pretty clear. It becomes more difficult though, as we look at the two words, in the sense of inte än, or inte ännu. The most accurate translation of that would be not yet. Here, the meaning is the same, as you can read in the example below:
Jag har ännu inte träffat mina svärföräldrar.
Jag har inte träffat mina svärföräldar än.
As you see, it is just a matter of position, with the former formulation a little more formal than the latter.
Coming back to även, which sounds very much like the English even . I do empathise with any attempt to use these equivalently, although this is rarely correct. Mostly, även would translate as too, or also, in order to add information to a statement. It is mostly used in written language, or formal speech. For example:
Han har jobbat som spansklärare i manga år. Han har även arbetat som översättare.
Restaurangen serverar kött och fisk. De har även en vegetarisk meny.
Mistranslations also often occur for even, in the sense of pointing out the exceptional. This should be translated as till och med:
Igår var det riktigt varmt i Göteborg. Till och med José, som är spansk, tyckte att det var jobbigt.
I hope that is useful. Please let me know if there is anything else that I could help to clarify.