Difference between sinkin and sorcing ports of different microcontrollers.

Can any one please explain the difference between 89c51 and 89s51? and what is the sinking and sourcing ports of microcontrollers.. i mean to ask what kind of microcontrollers have sinking ports and what kind of microcontrollers have sourcing ports?

Most have both. Look at the data sheets.

When a micro controller sources a part the IO pin provides the +voltage.
When a micro controller sinks a part the IO pin provides the gnd or -voltage.

It is possible to do both as you often see in charlieplexing (google it).