Yoghurt is the stuff that marinates (tenderises) the meat by breaking down the proteins in the meat (like other acidic substances such as lemon juice, other fruit juices, vinegar, wine, etc). Evaporated milk wont be doing that.
Being acidic, yoghurt generally adds tartiness (not really creaminess) to dishes. Evaporated milk, being sweet and creamy, will add sweetness and creaminess to a dish.