Difference between Much and More?

Hi,

I am confused about usage of More and Much. Sometimes, I get confused about what to use “Much’ or ‘More”

e.g.

I think compared to java PHP has more demand vs I think compared to java PHP has much demand.

or

People completed engineering have more chances of getting selected or People completed engineering have much chances of getting selected.

Is there any rule which helps to use Much or More correctly?

Please help me out.

Thanks!