a little bit和a bit是同义的.
a little bit与a little两个都能做为程度副词词组来用.修饰形容词,副词,动词和比较级结构.这时两者是可以互换的.意思是：“稍微,一点”如：
He is a little bit / a bit / a little taller than me.他比我高一点.
其次是这两个还可以用做为形容词词组,修饰名词,a little bit/ a bit后面要接of,再接名词,而a little是直接修饰名词的.如：
He has a little bit / a bit of money.
He has a little money.