Lingqs Learned vs. Known Words
Yes, a word became Known when you change it's status to 4 (or checkmark). However, as @nfera mentioned below, Known Words counter includes words only, not phrases.
LingQs learnt includes phrases, but known words does not. So 38 LingQs Learnt and only 28 Known Words means that you learnt 10 phrases (that is, multiple words like "logged in").
Aha, that's it. Thanks!