Eitthvaðand svolítiðboth translate to something in English; that’s just begging for a clarifying article. Let’s make these words a little easier to tell apart!
Do You Know What You’re Talking About?
The core difference is this: with eitthvað the speaker doesn’t know what the “something” is, while with svolítið they do know.
Here are some examples.
Hún sagði eitthvað sem ég heyrði ekki og hljóp svo út > She said something I didn’t hear (so I don’t know what it was) and then ran out.
Hún sagði svolítið merkilegt, en ég má ekki segja þér > She said something remarkable (and I know what it is), but I can’t tell you.
Það er eitthvað skrýtið á seyði hérna > There’s something strange going on here (and I don’t know what it is).
Það er svolítið skrýtið á seyði hérna > There’s something strange going on here (and I know what it is).
Ég ætlaði að segja þér eitthvað, en ég gleymdi því > I was going to tell you something, but I forgot what it was (and obviously I don’t know what I forgot)
Má ég segja þér svolítið? > Can I tell you something? (I know what I’m going to tell you)
If you’ve been mixing these up for ages and are now kicking yourself for sounding silly, let yourself off the hook. This is one of those things that feels super obvious once somebody’s pointed it out, but is really hard for the learner to notice in the first place.