What is the difference between a cnm and a cpm? Which type of midwife is more trained?

Different training. Cnm have a degree in nursing in addition to midwifery. Their training seems more geared towards in-hospital settings. Cpm do not have a degree in nursing, but do have training in midwifery.
CNM's have more . A cnm stands for a certified nurse midwife. They have degrees in advanced paractice nursing either at the doctorate or masters level. Cnms are extremely well-trained a cpm must have a high school diploma and then go through a certification process through the their own governing organization.