Too... To... With enough... To... And so... That... Difference

1. Too + adj./adv. to + V... and cannot do something
For example, he is too young to go to school.
He is too young to go to school.
2. adj./adv. + enough to + V. enough... to do something
For example, he is old enough to go to school.
He is old enough to go to school.
3. So + adj./adv. + that clause so...
For example, he is so old that he can go to school.
Generally, these three sentence types can be used for synonymous sentence conversion, as follows:
Too......
= Not antonym enough
= So... that negative sentence
For example, he is too young to go to school.
= He is not old enough to go to school.
= He is so young that he can't go to school.