“到达” and “达到” are similar in meaning and pronunciation, while they cannot be exchanged for different grammatical usage.
“到达” means “arrive at/in”, followed by the locative objects like the location, the target, the period and so on.
“达到” means “reach/achieve” like “达到a goal, a level or a standard.”
Then I will help you to comprehend the difference between “到达” and “达到” with some examples.