See.

I've been a physicist and am now a software engineer. I can use the maths based jargon in both those fields, but not vice versa.

That's partly because everyone in a STEM field had to learn at least some maths. But more importantly: maths is about the logical interconnection of things, while the things themselves are substitutable. So it is no suprise that its jargon can be applied in many fields.

Made me remember this. If only the 'upper' fields adopt mathematical naming where applicable :D

Substantial means that your result is big enough to have any practical import. In other words, is there any substance to the result?

For an example of a result that is significant but not substantial, suppose you find after surveying millions of people that members of demographic group X score 1/10 point higher than average on an IQ test.

For an example of a result that is substantial but not significant, sales figures are often so variable that it's impossible to determine with confidence whether even a 100% jump in revenues is due to a recent ad campaign or just a random fluke.