Hello @sachin16,
Thanks for sharing your question with the Klaviyo Community!
Klaviyo actually has a great Help Center article explaining the difference between a flow trigger and flow filters which you can find here: About Flow Triggers and Filters
Essentially, a flow trigger is the action taken by your customers to initiate them into a flow. Whereas a flow filter are rules and conditions set in place to either exclude or include certain customers from entering the flow.
Other Help Center articles I would suggest taking a look at to further see how flow triggers and flow filters work are the Getting Started with Flows and Objective Video: Flow Library articles.
I hope this helps!
David