not vs nowhere near

not

• To no degree. 

• Negates the meaning of the modified verb. 

• Used to indicate the opposite or near opposite, often in a form of understatement. 

• ‘Do they know?’ ‘I believe not’ (formal) 

• And not. 

• Used to indicate that the previous phrase was meant sarcastically or ironically. 

nowhere near

• Not by a large margin, not nearly, not at all.