Display Rules in Dynamics 365 are evaluated server-side, but Enable Rules are evaluated client-side. As a result, there are some types of rules that can be used in one but not the other.

For example, you can only use an EntityPrivilegeRule in a Display Rule, but a Custom Rule can only be used in an Enable rule.

Enable rules can be re-evaluated on demand using formContext.ui.refreshRibbon(refreshAll) to show/hide buttons dynamically based on changes to the field value on the form.

Display rules, on the other hand, will only be re-evaluated when the page is refreshed.

in the below screenshot you can see some rules can be used in Enable Rules are not applicable to Display Rule and vice versa.