这两个词在用法和词义上有不少差别：
1.deny常常作“否认，否定(背弃)”讲，其后可接名词、代词、动名词或that从句。例如：
deny a claim/a charge/an accusation
否认某种说法 / 指控 / 指责
He has denied his party and his principles.
他背弃了他的党和他的原则。
She denied any knowledge of her marriage plans on the papers.
她声称对报纸上关于她的结婚计划毫不知情。
He denies attempting to murder his wife.
He denies having attempted to murder his wife.
他否认企图谋杀妻子。
He denied doing any harm to the owner.
He denied having done any harm to the owner.
他否认坑害过物主。
He denied that his evidence about the telephone call was incorrect
他否认自己关于电话的证词是虚假的。
She denied that she had turned traitor.
她否认自己叛变了。
He denied that he had stolen the money.他否认曾偷过钱。
2.refuse 表示“拒绝”，含有非常坚决地、不客气地拒绝的意味。例如：
refuse sth. 拒绝……，意思是“不要、不接受”
I politely refused their invitation.
我礼貌地回绝了他们的邀请。
She refused my flowers.
她拒绝了我的鲜花。（refuse 后面跟名词）
=She refused to accept my flowers.
她拒绝接受我的鲜花。（refuse 后面是不定时短语）
refuse to do sth. 表示“拒绝做、不愿去做”
He refused to go home.他拒绝回家。
refuse作及物动词时，后面常常接名词或代词表示被拒绝的对象，例如：
He refused me.他拒绝了我。
跟不定式表示拒绝做某事。例如：
He refused to go home.
他拒绝回家。
记住，refuse不接that从句。
3.当表示拒绝把什么东西给某人时，这两个词几乎是通用的。
deny /refuse sb sth= deny /refuse sth to sb
被动形式：sth is denied/refused to sb
Sb is denied/refused sth
拒绝给予某人某物或某人被拒绝得到某物
也就是接双宾语时deny可以与refuse互换，不过语气要比refuse更坚决。例如：deny me a favor=refuse to help me.
Justice must not be refused/ denied to anyone, however poor he may be.
公平应该给予每一个人，不管他多么贫穷。
At that time education was refused/ denied to the working classes.
那时，劳动人民被剥夺了受教育的权利。
American women were refused/ denied the right to vote until 1920 after many years of hard struggle,
经过多年的艰苦斗争，直到1920年，美国妇女才不给予了投票权。
They were refused/ denied entrance to the exhibition.
他们被拒于展览会门外。
He was denied refused/entry to the country.
他被拒绝进入该国。
She was refused/ denied access to her children
她被禁止探视她的孩子。
They were refused/ denied access to the information.
他们试图取得这个情报被拒。
Access to the information was refused/denied to them.
他们无法得到这个情报。