Retrospective can be described as affecting or influencing past grievances by looking backwards and contemplating about the past.
"Really! What a retrospective method of thought."
Retroactive means expanding or extending in scope, effect, application and influence to a prior time or conditions.
‘Retrospective’ used as an adjective means looking back on past events or processes.
“The essay takes a retrospective look at the history of the Black Lives Matter movement since its founding in 2013.”
‘Retroactive’ is an adjective that means taking effect from a past date. It is often used in talking about laws or other legislation.
“The retroactive tax law will affect everyone who bought property since 2012.”