Flash memory is known to create floating-gate transistors. This also makes use of NAND type memory. EEPROM is known to be a type of memory device that can be used to erase or overwrite the data that you have placed. Take note that EEPROM makes use of NOR memory type. They are also different in terms of erasability.
For example, if you would try to erase FLASH, you can expect that this is block-wise erasable. On the other hand, it will be very different when you use EEPROM because this is byte-wise erasable. People usually choose the device that they want depending on what they are going to use.