Normally servers have an exp table with static numbers to tell how much exp you need to level. They also have a static number for how much exp a monster will give you.
Meliora has changed the static exp table to a mathematical calculation with smooth transitions between phases:
Phase
Levels
Difficulty
Growth Rate
1
1-10
Very easy
1.10
2
11-30
Easy
1.14
3
31-60
Moderate
1.09
4
61-90
Moderate
1.06
5
91+
Progressively harder
1.08+
After level 90, the difficulty increases every 30 levels (+0.01 growth rate per tier).
Different types of monster will also give different exp:
Rank
Multiplier
Small
x 1
Normal
x 1.1
Captain
x 1.2
Mid Boss
x 1.3
Boss
x 1.5
Higher level difference
The level difference between you and the monster will impact the amount of exp you will be getting. The exp reduction will be higher depending on the level difference.