Soft macro and Hard macro are categorized as IP's while being optimized for power, area and performance. When buying IP and evaluation study is usually made to weigh advantages and disadvantages of one type of macro over the other like hardware compatibility issues like the different I/O standards within the design, and compatibility to reuse methodology followed by design houses.
Soft macros are used in SOC implementations. Soft macros are in synthesizable RTL form, are more flexible than Hard macros in terms of reconfigurability. Soft macros are not specific to any manufacturing process and have the disadvantage of being unpredictable in terms of timing, area, performance, or power. Soft macros carry greater IP protection risks because RTL source code is more portable and therefore, less easily protected than either a netlist or physical layout data. Soft macros are editable and can contain standard cells, hard macros, or other soft macros.
Hard macos are targeted for specific IC manufacturing technology. They are block level designs which are optimized for power or area or timing and silicon tested. While accomplishing physical design it is possible to only access pins of hard macros unlike soft macros which allows us to manipulate the RTL. Hard macro is a block that is generated in a methodology other than place and route ( i.e. using full custom design methodology) and is imported into the physical design database (eg. Volcano in Magma) as a GDS2 file.
Firm macros are in netlist format and are optimized for performance,area and power using a specific technology node. Firm macros are more flexible and portable than hard macros. Firm macros are mode predictable in terms of performance and area when comparing with soft macros.