するとHaving done..., If...is done..., (And/just) then, Thereupon, If so

すると is often considered an abbreviated form of そうすると, and both are typically used at the beginning of a sentence to express something that occurred or logically followed from what came before, similar to 'upon (A), (B)' in English. Both can also be used to summarize or draw a conclusion from the previous statement, like saying 'so that means (A).'

The two Japanese phrases, すると and そのため(に), are used in different contexts. すると is used to indicate a natural or logical outcome or consequence of a certain action, it is often translated as 'and then', 'if', or 'when'. On the other hand, そのため(に) is commonly used to express the cause or reason for a certain outcome, it is often translated as 'for that reason', 'because of that' or 'hence'.

と marks a natural result, while すると is a transition word meaning 'thereupon' or 'and then'. It's often used at the beginning of a new sentence to show what happened next. For example, ドアを開けた。すると、猫がいた ('I opened the door. And there was a cat.'

Both describe what follows from a previous situation, but with different nuance. そこで introduces an intentional response to a situation, e.g. 雨が降ってきた。そこで傘をさした ('It started raining, so I opened my umbrella.') すると shows a natural or immediate result, e.g. 雨が降ってきた。すると子供が泣き出した ('It started raining. Then the child started crying.')

すると and それに are both sentence starters but differ in usage. すると shows result or reaction, e.g. 雨が降った。すると傘を差した ('It started raining. Then he opened an umbrella.'). それに is additive and neutral: 雨が降っていた。それに寒かった ('It was raining. And cold too.').