Hmmm. interesting question! "pace' is the rate (speed) at which something moves. It is often used in set expressions: The pace of life has changed since I was a child. People in southern countries live life at a more relaxed/slower pace. You can see more expressions/set phrases and sample sentences here: https://www.ldoceonline.com/dictionary/pace We usually use speed when we are talking about something going FAST the speed of light speed of change in the tech industry is incredible-- this would be faster than the pace of change (I know -- confusing!! The pace of change in government regulation -- meaning there's a very slow change ) The speed of growth -- this would connote a fast change in growth I hope I haven't confused you even more!

I think the answer to this question depends greatly on the context these words are used in. But generally speaking ‘speed’ refers to how quickly or slowly a person or thing functions or how much distance a thing or person covers. For example: the speed of the internet determines how fast or slow your internet will function. A car can usually reach much higher speeds than a bus. ‘Pace’ refers to how quickly or slowly someone or something functions over a period of time. For example: If you eat too quickly you will get a sore stomach. You should slow down your pace. You are playing the music too slowly. You should speed up the pace. So basically speed can refer to how quickly or slowly someone or something is functioning or can function at a specific moment in time. And pace refers to how quickly or slowly someone of something is functioning over a period of time.

Pace is most commonly used for walking.running, or moving (often used in sports). Pace is the rhythm or minimum constant speed needed to achieve something. This is why you often see "pace makers/ setters" in long-distance running races, who's job it is. Is to set a pace for the hopeful winner to follow until the closing stages of the race. You will hear commentators referring to this very often. The most successful racers have the ability to "pace themselves" To set a pace you set up or decide how many steps/strides/ revolutions of an engine to constantly achieve to get to somewhere at a set time. Speed is the velocity or distance covered in a set time. The two are closely connected and can sometimes be interchanged. "the pace of change in computer memory is currently double every six months" Every six months computers are made that have double the memory. "the speed of light or sound is a known figure" the speed of light or sound etc does not alter its pace or even speed. They are both set firmly in the known science of physics. A car speeds up when The engine is reeved it goes faster, when the rate (pace) of engine piston strokes per second is increased.