There are many different kinds of pitch/note systems at use around the world but the two big ones, 12 Tone Equal Temperament (12TET) and Just Intonation, both feature scales that are derived by mathematical formula and, so, feature consistent scalar relationships inside a given key. In other words, a perfect fifth pair has the same mathematical ratio no matter what key it's in within

*either* system -- but the ratio of such pairs IS different when comparing the temperament systems to one another.

https://en.wikipedia.org/wiki/Just_intonation
https://en.wikipedia.org/wiki/Equal_temperament
Here's a chart that compares the ratios in each system for each step of a scale:

https://en.wikipedia.org/wiki/Equal_...ust_intonation