This is a great area of concern for all the new parents. Here, I would like to clarify that this entire process is totally different from adults, and babies follow their own rules.
The first and foremost thing you should remember is that it is not fixed how many times your baby will pass stool in a day. A breastfeeding baby may pass stool once a week which is absolutely normal and it should not be considered as constipation. This happens because breast milk contains very a much smaller number of solid materials which can be passed as a stool. Therefore, it is not mandatory for your baby to pass stool regularly like adults.
Moreover, a constipated baby will have difficulty in passing stool. The symptoms may be, the baby will consume less milk, the baby may vomit, the stomach will swell and the stool will be like small rounded balls.
On the other hand, a normal breastfeeding baby may pass stool on regular basis and several times a day. It cannot be considered diarrhoea. In case of diarrhoea, the stool will be liquid, it will be frequent, dehydration will be observed and the baby will be very weak. But generally, it is observed that a breastfeeding baby possesses very little chance of diarrhoea.
In a nutshell, a completely breastfeeding baby may pass stool several times a day to once a week.