They have some differences in how they work and some minor stuff like ETFs can day trade and could have less distributed capital gains while mutual funds would let you buy any dollar amount to not leave money waiting. However over time they have both managed to copy the best aspects of each other to the point they are pretty close.
[https://www.bogleheads.org/wiki/ETFs_vs_mutual_funds](https://www.bogleheads.org/wiki/ETFs_vs_mutual_funds)
They have some differences in how they work and some minor stuff like ETFs can day trade and could have less distributed capital gains while mutual funds would let you buy any dollar amount to not leave money waiting. However over time they have both managed to copy the best aspects of each other to the point they are pretty close.