Economic vs Economical etc

[Unregistered]

I have a question about how to explain when to use the -al, for example economic vs economical and historic vs historical. Both can be used as adjectives, correct? But what else? Thank you!

[svartnik]

I have a question about how to explain when to use the -al, for example economic vs economical and historic vs historical. Both can be used as adjectives, correct? But what else? Thank you!

all four are adjectives:

historic=important in history
economic=related to economy
economical=frugal
historical=related to history

"I have a question about how to explain when to use the -al,"

Your question rightfully turnes up looking at the examples.
My answer is "I do not know."