Health savings accounts $($HSAs$)$ are different from flexible spending accounts $($FSAs$)$ in that:

FSAs allow for medical expenses to be paid using pre$-$tax dollars, and HSAs do not. HSAs allow for medical expenses to be paid using pre$-$tax dollars, and FSAs do not.

FSAs allow contributions to be saved long$-$term, and HSAs do not.

HSAs allow contributions to be saved for the future, and FSAs generally do not.