All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The obligation of the children towards their parents in regard to being kind and dutiful to them and spending on them if they need support do not differ according to the difference of the sex of the children. However, the way the parents deal with the children may differ according to the sex of the child. For instance, a daughter is permitted to see and touch the parts of the body of her mother that the adult son is not permitted to see or touch.
Therefore, the examples which are mentioned in the Fataawa to which you referred are in this context. The difference is that the 'Awrah (parts of the body that must be covered in Islam) of the mother with her daughter is from the navel to the knee. This means that the mother is permitted to breastfeed her daughter, while her son is not permitted to see from his mother except what she is usually permitted to reveal, like the head, the neck and the like, as discussed in the above-referred Fataawa.
For more benefit, please refer also to Fataawa 84062 and 90591 which clarify that the difference is due to the sex difference and not in regard to the rights of the parents on the children according their gender.