250 MHz clock — timing margin on the bus
At 250 MHz the part delivers a 4 ns cycle time. That is the same clock rate as the 72Mbit CY7C1512KV18-250BZC (also 250 MHz, but 4M x 18).
4M x 36 organization — what the width means
The 36-bit data word matches a 36-bit bus common in network processors and high-end FPGAs. The 4M depth gives 144Mbit total. If your design uses an 18-bit bus, the 8M x 18 CY7C1613KV18-333BZXC (333 MHz) is the same density but narrower, trading speed for bus width. No rewiring between the two — different pinout, different footprint.
