The difficulty of Normal Content in this game needs to increase.

[BigCheez]

Then why is it called
a Variant?
b Criterion?
C Savage Criterion?

If the the middle one b is also Savage difficulty?

Variant and criterion are named differently because they are significantly different in terms of the structure of the content. Criterion savage is just a difficulty increase on top of regular criterion, so they just stuck "savage" on the end.