Tactics vs Strategy in Chess and Positional Play

I have often heard people talking about tactics and strategy when analyzing games. These two terms seem to be used in an opposite context even if I am not really sure one can define them in an absolute way. As far as I understand a tactical move is one that serves a spesific purpose in a spesific position and might not express the general principles of chess. On the other hand a strategical move would be one that has no immediate threat coming out of it but is generally considered to be good. For example the positioning of ones pieces in better places during the opening or the capturing of the pawns towards the center. If this definition is correct, then positional play should originate from the combination of strategy and tactics in an almost invisible way. This is so obvious in games of great chess champions. Sometimes they play moves that one cannot comprehend no matter what.