What do you call it when the flow is much less than a water main break level?

Excessive leakage.

It’s still a leak. It’s a big leak or a small one, but regardless, it involves a broken pipe underground.

“A broken pipe” or “a leaky pipe”.

Water mains are large pipes, usually 8 to 12 inches in diameter, and pressurized. Water pipes from the main to your house are usually two inch pipes; they can’t deliver as much water as the main.

Restricted Flow

I guess I have to find someone who actually does the paper work in this area. They are all leaky pipes major ones minor ones medium sized ones, am I right?

It would depend on what size the pipe was that the leak was originating from.

@kritiper What do you call the different pipe size leaks?

It could be considered a minor leak if the leak was off a 24” main or a major leak if it was off a 1” line off the main into a house.
If the water is visibly flowing (and not seeping) out, and running in a stream down the gutter, I would call it a considerable leak.
You could always try to rate it in GPM.

https://www.hy-techroofdrains.com/water-flow-through-a-pipe/ I guess that’s what GPM means.
Thanks @kritiper

Uh, yeah, “gallons per minute.”