1)To say that two things are similar, we use the same :

as.
than.
then.
like.

2)We use 'elder' as a comparative form of the adjective 'old' :

to talk about friends.
to talk about people in a family.
to talk about all people.
to talk about children.

3)We use as + adjective + as to show that :

two people or things are not equal.
two people or things are equal.
two people or things are not similar.
two people or things are different.​