Through context. Most languages are like that. Heck, some languages, like Japanese and Tagalog, don't have the present, past or future tenses but what they call the "perfect" and "imperfect" tenses. Anyway, the two have close definitions and you'll usually be able to differentiate them through context.
As it's discussed in pretty much every previous lesson, English is the one of the few Germanic languages that actually distinguish the two tenses, Icelandic being another one. Another Germanic language - Dutch, expresses the continuous aspect, not with a different tense but with different constructions such as using one of the 'posture verbs' - 'Ik lig te slapen' - I am sleeping or literally 'I lie (down) to sleep'.
Correct (mokane3562) and I find myself sort of asking the same question, because one sentence is the cook presently drinking coffe, and the other sentence is saying that the cook does drink coffee not saying that the cook is at the present, but just saying that he/she does.