Instrumentation Question

What is the difference between Loop response and Process Response?
I have looked through many books and on the web for this answer and can't get a streight answer. Can you help?

I dont know for sure but I will state what I "think" I know and maybe someone with more expertise will correct it.

Loop is a term used with something like PID control, the control is regulated by a feedback device. The response is the time period between input from feedback and correction of regulation.

Process response is the time period it takes for a device to activate...ie a plc turns on an output which in turns activates a solenoid valve which extends a ram.

Explaining things like this is not one of my strong points. I have stated it as I understand it but it may not be fully accurate.

I've spent most of my process control life in the chemical industry (over thirty years) and there it's not uncommon for process response times to last for hours or even days. Effectively these are actually PID loop response times, but because the times concerned are so long, they are usually referred to as Process response times.

Whether this can be transferred to other areas, I've no idea. The term may well have another meaning in other branches of industry.