Both そして and そしたら translated by most dictionaries as THEN. Is there any difference in usage between these conjunctions?
"Then" has many meanings. Let's first look at an English dictionary.
- : at that time
- a : soon after that : next in order of time
// walked to the door, then turned
b : following next after in order of position, narration, or enumeration : being next in a series
// first came the clowns, and then came the elephants
c : in addition : besides
// then there is the interest to be paid
- a : as a necessary consequence
// if the angles are equal, then the complements are equal
b (1) : in that case
// take it, then, if you want it so much
(2) —used after but to qualify or offset a preceding statement
// she lost the race, but then she never really expected to win
c : according to that : as may be inferred
// your mind is made up, then
d : as it appears : by way of summing up
// the cause of the accident, then, is established
そして derives from そうして, which literally means "do so, and". Thus when you use it between the sentences, it roughly means "after that". It corresponds to the definitions under branch 2 above.
そしたら is likewise the contraction of そうしたら, which means "if have done so". If you translate it using "then", it'd be basically 3a, b(1) in the list (because other definitions are not conjunctive).
Usage-wise, そして is already an established word even if it's a contraction, while そしたら is still counted as non-standard, colloquial form of そうしたら.