I’ve worked with one of these machine builder companies before, and I’ve learned a lot of things about them, specifically about machines. From what I know, a mechanism can be a part of a mechanical system or a larger process. It’s also defined as the means of controlling, constraining or transmitting relative movement. On the other hand, a machine is considered as a collection of mechanism that transmits both the motion and forces. In short, the main difference between these two is that machines transform energy to do work while the mechanism will carry out this function. You can check out this link: https://www.cs.cmu.edu/~rapidproto/mechanisms/chpt2.html if you want to know more.