In paging, blocks of equal size (called pages) are transferred between the main memory and a secondary storage device, while in swapping, all the segments belonging to a process will be moved back and forth between the main memory and a secondary storage device.
What is Swapping?
Swapping is the process of moving all the segments belonging to a process between the main memory and a secondary storage device. Kernel would move all the memory segments belonging to a process in to an area called swap area. When selecting a process for swapping, the operating system will select a process that will not become active for a while. When the main memory has enough space to hold the process, it will be transferred back.
What is Paging?
In Paging whole process is divided into equal size pages and stored in the virtual memory (storage). The operating system copies a certain number of pages from your storage device to main memory. When a program needs a page that is not in main memory, the operating system copies the required page into memory and copies another page back to the disk. By this method OS is able to execute the process which is larger then the memory itself or the list of processes simultaneously larger then the memory.