ETFs are better than mutual funds in a taxable account. It gets complicated for why, but its just slightly more tax efficient. Mostly splitting hairs.

Also, FZROX can only be owned through Fidelity, so if you ever wanted to leave Fidelity, you'd have to sell your FZROX and incur a large tax penalty. With a retirement account, this isn't an issue.

ETFs though are portable and can go to any brokerage.