Hi, Muralidhar,
The SPIFI focuses on interface with SPI flash only, the SPI is an interface which can connect to a lot device including flash.
Regarding the difference, the normal SPI module has 4 signals: /SS, SCLK, MOSI and MISO signals, the /SS, SCLK and MOSI are driven by SPI master, the MISO signal is driven by slave. The normal SPI can interface with single I/O SPI flash.
The SPIFI interface includes /SS, SCLK and dual/quad/8 data lines, the data lines are bidirectional, they can input or output. In general, the Data0 line is command line, it transfer command to flash in the first phase, then the spifi module transfers address by all data lines or just data0 line, then spifi can transfer data depending on the command.
The SPIFI can generate the timing to access spi flash.
I attach the RM of SPI flash, pls refer to the doc to know the required timing of spi flash.
Hope it can help you
BR
XiangJun Rong