Too and enough indicate degree. They modify adjectives, adverbs, and nouns.
Too is an intensifier that expresses that something is inadequate (below what is desirable) or excessive (above what is desirable). The expression is complemented by an infinitive (nonfinite infinitive clause).
|Jill is too young to drive. (She cannot / may not drive.)|
|The car is too complex for her to drive. (She cannot drive it.)|
|The driving test is too difficult for her to pass. (She cannot pass it.)|
Enough expresses that something is adequate, within what is desirable. The expression is complemented by an infinitive (nonfinite infinitive clause). The infinitive may include a subject introduced by for. [for her] to do.
|Jill is old enough to drive. (She can / may drive.)|
|The car is simple enough for her to drive. (She can drive it.)|
|The driving test is easy enough for her to pass. (She can pass it.)|
Use of too and enough
1.Enough comes after adjectives and adverbs:
ADJECTIVE + ENOUGH or ADVERB + ENOUGH
He isn't old enough to watch this program.
We're not walking quickly enough.
2.Enough may also precede nouns:
ENOUGH + NOUN
We have enough money .
I have not got enough money to buy this computer.
3.Too comes before adjectives and adverbs:
TOO + ADJECTIVES or TOO + ADVERBS
It's too hot to wear that coat.
I was driving too fast.
4. Too may also come before nouns when it is used with the expressions too much and too many.
a. Too much is used before uncountable nouns.
TOO MUCH + UNCOUNTABLE NOUNS
There is too much salt in this food.
b. Too many is used before countable nouns
TOO MANY + COUNTABLE NOUNS
There are too many students in this classroom.