Elder-Older | Commonly Confused Words

Elder

/ˈeldə/

A person who is older or higher in rank in a group or society

/ˈəʊldər/

Having lived or existed for a longer time

Elder often implies seniority and is used more in the context of relationships within a family or community, like elder brother.
Older is a comparative form that is generally used when comparing age without implying hierarchy or authority.
Remember that elder is often used as a title or to show respect, while older is purely an age comparison.
In situations where family or lineage is emphasized, elder is more appropriate.
Older does not have any connotation of respect or formal position.