"Whereas the tactician knows what to do when there is something to do, it requires the strategist to know what to do when there is nothing to do” - Abrahams

However:

"‘At many stages of the game the general choice is available; what to do now that there is no coercion? Epigrammatically, it may be said: Tactics are what you do when there is something to do. Strategy is what you do when there is nothing to do. That isolation, however, is rare. Strategy is a feature, albeit unobserved, of most good tactical play. It is latent – not patent.’ -Abrahams

"‘Think strategies when it’s your opponent’s turn to move; sort out the tactics while your own clock is running." - Hartston

The legendary quotation goes
"Tactics is knowing what to do when there is something to do; strategy is knowing what to do when there is nothing to do" - Tartakower (apparently!)

"To the average player there is no, or little, distinction between strategy and tactics. Yet he will be a better player if he can perceive that distinction and turn it to account.

We might simplify considerably and say that strategy is the art of constructing advantageous situations, while tactics is the art of turning these advantageous situations into victory.

If the first explosion of the atomic bomb is considered as tactics, then all the planning, the calculations, the experiments, the interchange of knowledge, the organization of diverse skills, the stockpiling of needed materials – all these elements comprise strategy.’" - Fred Reinfeld

"‘Strategy is concerned with the setting of an aim and the forming of schemes. Tactics are concerned with the execution of the schemes. Strategy is abstract, tactics are concrete. Expressing it in a popular way: Strategy requires thought, tactics require observation.’" - Max Euwe

"Until you are at least a high Class A player: Your first name is 'Tactics', your middle name is 'Tactics', and your last name is 'Tactics'." -- Ken SMITH

"Many amateurs think that master games are usually decided by some deeply-laid plan covering all possibilities for at least ten moves. It is still true that most games, even between the greatest of the great, are decided by tactics or combinations which have little or nothing to do with the fundamental structure of the game.

"To take one striking example, look at the games of the Euwe-Alekhin matches. Euwe is a player who analyses openings ad infinitum, i.e., one who wants to settle everything strategically. Alekhin is likewise adept at the art of building up an overwhelming position. And yet in almost all cases the outcome depended not on the inherent structure of the play, but on some chance combination which one side saw and the other side did not. Tactics is still more than 90% of chess." - GM Reuben Fube