1、意思上的区别
in spite of ：不顾;虽然， 尽管…;别看
In spite of her hostility, she was attracted to him
尽管自己心存敌意，她还是为他所吸引。
regardless of：不管， 不顾;无;不拘
The fields give high and stable yields regardless of climatic circumstances.
不管天气条件如何，这块地总是保持稳产高产。
2、用法上的区别
in spite o一般是主观上故意去忽视,有时往往是好的条件,因素,或他人的建议,很可能导致不好的结果。
In spite of one or two minor mishaps everything was going swimmingly.
尽管遇到了一两件小小的不幸，一切都进行得很顺利。
regardless of 不管;不顾;不理会.后常接名词或者接从句，一般用于客观上无法避免的事实,往往是不利的条件,因素,需要主语去正确面对和处理,并不是避而远之。
All should be treated equally regardless of social status.
人不分贵贱。
扩展资料
regardless 的同义词为：despite、although
1、despite
英 [dɪˈspaɪt] 美 [dɪˈspaɪt]
prep.不管;虽有;尽管（自己）不愿意;不在乎
n.侮辱;憎恨;怨恨;轻蔑的拒绝或不承认
Despite myself, Harry's remarks had caused me to stop and reflect.
哈里的话让我不由自主地停下来细想。
2、although
英 [ɔ:lˈðəu] 美 [ɔlˈðo]
conj.虽然;尽管;但是;然而
He was in love with her, although he did not put that name to it.
他爱着她，虽然他没有将其称为爱。