(Not Viet fluent) If you look at individual words, tìm is seek and hiểu is understand. So it's "seek to understand" vs "study/learn". Same general sense, I guess you choose depending on what exactly you want to convey.
"tìm hiểu" here has this meaning of inquiring or looking into something
How does one know when to use 'learn about' vs 'get to know' when defining "tìm hiểu"?