The major differences are:
1) The ISRC pin is not available in the MAX1464.
2) The VB pin is not available in the MAX1464
3) In the MAX1464, the external reference voltage is limited to 2.5V (1/2 of VDD) only.
4) PGA gain setting can be applied on the temperature conversion in the MAX1464.
5) In the MAX1464, the temperature sensor has a positive slope (it is negative in the MAX1463) and it can be gained.
6) For other minor differences, refer to the MAX1464 data sheet.
7) Please also see knowledge base (support portal) for the register definition differences.