Difference between NOR & NAND flash

Comparison between NOR and NAND are:-

1> Size of an erase block in NOR ranges from 64 to 128 Kbytes, which means its write/erase operation can take up to 5 s, whereas

Size of erase block of NAND ranges from 8 to 32 Kbytes, which means its write/erase operation takes 4ms of time.

Therefore,
NAND has high cell densities due to which its "write" and "erase" programs are faster than NOR flash.
2> EASE OF USE:-

NOR flash has an SRAM interface. It has enough address pins, through which allowing for easy access to every byte contained in it.

NOR-based flash is a straightforward process. It is connected like other memory devices, and code can be run directly from it.


NAND device, however, is complicated with its requirement for an I/O interface. Accessing rules for NAND interfaces may differ depending on the NAND vendor.

A driver must be written and used for performing any operation on a NAND device.

Therefore,
NOR "reads" slightly faster then the NAND flash.

3> NOR devices are used as a code-storage media.
NAND devices are used as a data-storage media.