1)
What is the "Nefesh Ayefah"?
1.
Radak: It is the Nefesh of Yisrael, which was tired and thirsty in exile. I satiated it from the springs of salvation.
2.
Malbim: It is one who was tired from great work.
2)
What is the "Nefesh Da'avah"?
1.
Radak: It is sad and worried from the many afflictions. I filled it with all good so it will be happy - the opposite of Da'avon. Also Yonason translates like this.
2.
Malbim: It is sad due to lacking its needs. I filled it with all its needs. They weakness need to extort or steal; they will dwell in the place of Tzedek.
