"He drinks milk and eats the bread."
Translation:Dia meminum susu dan makan roti.
Hai! I think both are used as verbs with the same meaning, and with no difference between formal or informal use. In colloquial speech, I think verbs as "minum" and "makan" are more used than "meminum" and "memakan". In writing, I think "meminum" and "memakan" can be used to show a better knowledge of the Indonesian grammar, but this use is not always necessary. It is also recommended for official documents or letters, newspapers, but I insist in my opinion that they are not intended to be formal. Evidently, people can also use them in formal speech or not.
Selamat belajar! :)