I often hear people use one of these words as a substitute for the other word.

Problem:
The words “entitled” and “titled” are not synonyms.

Explanation:
One definition of the transitive verb “title” is to call by a name.

An example of proper use of this verb is “He titled his autobiography ‘Jim’.”

One definition of the verb “entitle” is to give (a thing or person) a claim to something.

An example of proper use of this first definition of “entitle” is “American children are entitled to a tax-funded education.”

Another definition of the verb “entitle” is to confer an honorary title on (someone).

An example of proper use of this second definition of “entitle” is “The king entitled him Sir Muckety-Muck at the polo match.”

A third definition of the verb “entitle” is to give a title to something, but it does not refer to the title itself.

So it is incorrect to say or write “He entitled the book ‘Babe Ruth’.”, but it is correct to say or write “He entitled the book before he wrote it. It is titled ‘Babe Ruth’.”

In other words, one should not use “entitled” before the name of a movie, rock concert, book, athletic competition, painting, etc., but one may use “titled” before the name of any of these.

Solution:
Use “titled” but never “entitled” before the name of an event or creation.