What tier meanings actually mean

Everyone is so caught up in tiers from purely status but they actually tell a lot about chapters cultures and there are reasons why chapters fall into each. That’s why different people prefer different chapters

Top- partying is priority.
Middle- better balance between partying and other aspects of Greek life
Bottom- less emphasis on partying more emphasis on the other aspects of Greek life.

Of course there are exceptions to every rule but this is generally how things are.