The PB-770 have a hot key to mathematical functions similar to those of later Casio (FX-700p, 720p PB ...).
Both PB-770 offer a range of statistical functions.
Default, the PB-700 has 4 kb of memory, the PB-770 has 8.
The PB-700 may board three OR-4, 4 kb extension memories, for a total memory of 16 kb.
The PB-770 may board three OR-8, 8 ko extension memories, for a total memory of 32 ko.
the Japanese version of PB-770, unknown in Europe, has a KATAKANA key for access to Japanese characters. On PB-700, the characters are available through CHR$() Basic function.