What is the difference between commendation (tazkiyah) and praise (madḥ)?

The meanings of tazkiyah (self-praise/purification) and madh (praise) are similar. Tazkiyah is praising the self, describing it, and commending it. Madh is good praise. There is hardly any difference between them. If there is a difference, tazkiyah is more specific in negating imperfection than madh.