这个英语句子的that意思
Theforeignresearchscholarusuallyisolateshimselfinthelaboratoryasameansofprotection;however,whatheneedsistobefittedintoahighlyorganizeduniversitysystemquitedifferentfromthatathome.
最后的differentfromthatathome的这个that是什么意思
求详细点.谢谢