What is the difference between Microsoft office and Hancom Office suite.? Which is good for business and why?

I haven't heard of Hancom so I can't give you  direct answer but there are several free office suites that do everything MS Office can do and don't cost a cracker.  I've used both Apache Open Office and Libre Open Office. Both are excellent.

In a business environment it might be better to stick with MS Office, if only because most staff training courses will focus on them and if you get a youngster without much experience they may have difficulty making the (slight) transition from one to the other.