SUBTLE MIND VS. LOVING-KINDNESS:
Really the two practices work interchangeably to develop our minds, body and spirit. Although the Subtle mind practice gives an opportunity to observe how the mind works with mental movements (Dacher, 2006).
The loving-kindness practice seems to focus on healing through forgiveness and loving kindness.
Mental and physical wellness are similar in that our nervous system is our mobile messenger and we it goes back and forth from mind to body and back again. So the correlation between the two is similar and can help us teach our mind to achieve goals physically as well.
Using Yoga for me is a mind-body practice that I try and use daily, for relaxation and to bring myself more in touch with mind/body. It is relaxing and after words I feel stretched, relaxed, calm, and at peace.

Reference:
Dacher, E. (2006). Integral medicine: the path to human flourishing. Basic health publications.