Is there any difference between вероятно and наверняка in expressing assumptions?

Question

I believe that both of these adverbs are used to express "must" in assumptions. I wonder if they're completely synonymous, or if one carries a different set of semantic nuances from the other?

Наверняка/вероятно вчера с Андреем что-то случилось.

Something must've happened to Andrey yesterday.

(... he never showed up, etc.)

Answer 1

The exact meaning of the words are as Vi said, one shows a high probability and the other a certainty. In usage, however, they are both used to express the same concept but, Наверняка is colloquial while Вероятно is more literary.

Answer 2

• "Вероятно" is like "probably" or "likely";
• "Наверняка" is like "for sure".

If the statement about Andrew's calamities is expected to be overestimated (i.e. a mother which always worries about her son), "наверняка" may sound better.

Answer 3

It might be added that until (I believe) around the early XXth century "наверное" meant "certainly" whereas today by some reason "наверно" seems to be more towards "вероятно" than "наверняка"