What's the difference between 1kb(64x16) and 1kb(128x8) for EEPROM memory size?
64x16 means that the memory is arranged as 64 words of 16 bits each.  128x8 means that the memory is arranged as 128 words of 8 bits each (i.e., 128 bytes).  You read, erase, and write on a word-by-word basis.

In general, wider words are faster, but because you must erase an entire word at a time, they're less convenient.

Those are some pretty old memory chips you're looking at!