C major=........ P1-M2-M3-P4-P5-M6-M7-P8
A minor=........ P1-M2-m3-P4-P5-m6-m7-P8
D dorian=....... P1-M2-m3-P5-P5-M6-m7-P8
The D hypodorian has its root a fourth below the tonic of the dorian, which means that the root of the hypodorian has a ratio of 3:4 or 1:1.333. and the root of the dorian has a ratio of 1:1

Again the G Mixolydian has its origen on the G major scale, and then you flat the 7th, making it relative to the C major scale.
The series of intervals in the mixolydian are:
P1-M2-M3-P4-P5-M6-m7-P8
So we are taking about a different mode.

And I was trying to demostrate how those scales are different in terms of Frequency ratios as well.
In the G mixolydian for example, "A" is major second and it has a ratio of 9:8,
So, in terms of intervals and in terms of frequencies, none of those scales are the same; they are relatives.
Please don`t get me started with frequencies, because that can be confusing, all I`m saying is the hypodorian is not a dorian, nor an aeolian, nor a mixolydian. It is a Hypodorian.