What can persist after legal abolition?

Your list can be understood like this:

Social practices

What people do.

Example:

discriminatory treatment of Black people.

Social attitudes

What people believe or assume.

Example:

beliefs that Black people are naturally inferior.

Economic relationships

How people are positioned in relation to production, labor, property, and income.

Example:

landowner and landless worker.

Institutional patterns

Established ways in which institutions operate.

Example:

racial exclusion within political or educational institutions.

Legacies

The continuing effects of earlier historical conditions.

Example:

the effects of having been denied property accumulation under slavery.

Racial hierarchies

Differences in social status and power associated with race.

Importantly, after emancipation this is not necessarily the same legal hierarchy that existed under slavery.