The main difference between the MAX17000 and MAX17000A is the SMPS operation when STDBY=low. This is why the MAX17000 features Low Quiescent Current Standby State while the MAX17000A doesn't. Below table shows the difference operation of the SMPS when STDBY=low
MAX17000 vs. MAX17000A Design Differences
MAX17000
MAX17000A
STDBY = Low turns off VTT and overrides the SKIP setting, forcing the SMPS to enter a low-quiescent current ultra-skip mode.
STDBY = Low only turns off VTT rail, and does not affect SMPS operation.