一、褒贬不同——侃侃而谈、夸夸其谈。它们都是形容说话的,前者形容从容不迫的说话态度,是褒义。如“他引古论今,侃侃而谈。”后者是评论说话的内容浮夸不实在,是贬义。如“他整天东奔西窜,到处指手画脚,夸夸其谈。”二、对象不同——不堪设想、不可思议。它们都有“不能想象”的意思。前者适应的对象是严重的不良后果,后者适应的对象是奇妙的事物或深奥的、不可理解的事情或道理。 First, praise and criticize different - talked about, rhetoric. They are all described as speaking, the former described unhurried attitude of speech is commendatory. Such as “He cited the ancient theory of today, talking about. ” The latter is the commentary to talk about the content of exaggeration is not real, is derogatory. Such as “He went all day long run channeling, hand gestures everywhere, rhetoric. ” Second, the object is different - unimaginable, incredible. They all have “can not imagine” meaning. The former adapt to the object is a serious adverse consequences, the latter to adapt to the object is a wonderful thing or esoteric, incomprehensible things or truth.