You are actually talking two different caramels. The caramelizing sugar one is exactly that-caramelizing sugar. The second method is actually a Maillard caramel-you are caramelizing the protein in the dairy. You get different flavor profiles from each. In my experience, you have to cook the first method to a higher temp to get it to “stand up”. For a sauce or a pipe able caramel, I use the caramelized sugar method. For a stand up caramel, I use the Maillard. Just personal preference. Remember you have to adjust final temp for your altitude.