As found by those Islamic scholars the immediate disagreements are : Communism calling for a classless society ( I suppose social class, political class and economic class - abolition of money ) and for abolition of private ownership of land, property etc.
I will call for a compromise between the two by :
1. Allowing for a money system but seeing to it that no person is able to accumulate money and become artificially richer than another because money after all is an artificial concept. Please read
this proposal of mine.
2. Allowing for a person or group to use big items like land, property, office furniture, office machinery etc to their fullest but the ownership of those items ultimately be by some system-level committees that manage resources on behalf of the people. I will further tell you why total private ownership is not good. In India there are 40 million pending, unresolved court cases at various court levels ( Supreme, High etc ) ! Many of these cases will be of land, property and other privately owned items and some of them will involve violence waged by the disputers. All of that chaos, crime and those millions of pending cases would not have existed if the citizens would have been disallowed to totally privately own those items.
A further difference is that Islam recognizes the family system as one of the fundamental units of society and allows facilities for it in form of marriage law and inheritance law but some Communists, at least in the early days of the USSR, spoke about doing away with the family system on grounds of setting up a more scientific society. I think we as the human race will have to revisit this issue when we begin setting up Mars settlements and may have to ultimately resort to creating children in artificial wombs to account for environmental and social difference on Mars and those children then raised in hostels until the age, say 15, when they attain mental maturity and are sufficiently educated to either be furthered educated in advanced schools ( say medicine ) or are put into the workforce.