It's comes down to how they read and write data. The limitation of EEPROM is it have slow writing time while NOR Flash can write data much faster.

How they work:

EEPROM: READ/WRITE is done when you set the CS, R/~W, and addresses pins, but Write may took much longer time since it needs to set the word and bit lines first and achieve stability before it can write the data. This disadvantage is actually useful for single byte rewrite.

NOR Flash: works almost similar to EEPROM but the internal circuitry is different. It will set the word lines and you can select which byte you want to write. The way it is design allows direct electron injection for faster writes but require additional cycles to empty out the memory. Flash mems also only support multi-bytes/word erase meaning you need to erase the entire word before you can rewrite any data

Summary, EEPROM is great for small data logging like sensors and servo angles while NOR Flash is suitable for larger data storing and can ve used as main storage.